one big of a [noun]

I abide by the Edwin Ashworth's point of view on the issue in question (as to the lookout for the usage of the phrase and its relevance).

From a grammatical point of view:

1. On the one hand "one" can be an adjective meaning "very" that can be put in instead of the Indefinite article before adjectives:

• "She was keeping a very big secret = She was keeping one big secret", and (from "Your Secret Keeper" by Alison Charm): "[the man might have turned to Teresa to escape from further scandal, but] She was keeping one big of a secret";
• (from "Love of a Vampire") "He is blue eyes blonde hair guy who looks hot and one big of a flirt person"

2. On the other hand "one" can be a noun:

• (from Urban Dictionary) dekahs is another name for a worm - "Hey look at that worm (...at that one)! [That one is very big] That's one big of a dekahs";
• (from an article on www.thealleytheater.org "For Your Inspiration: The Golden Rules of Designing an Open-Concept Space") "It’s a bit more difficult to arrange a space in an open-concept, precisely because you just have one big of a box to fill (...you have one [box] to fill) — with no walls, no furniture yet, and no guideposts whatsoever".

3. (some more live examples)

• "Let's face it. Starting a business is one big of a headache". (www.horeca.co.il);
• "Three years later here we are and were trying it with a bang and it’s one big of a bang since we grabbed their Yang Dinner Menu with some Beverage Package on our most recent team dinner." (from a blog of a New Zealander about a restauraunt Madam Woo, North Shore City, New Zealand on www.angsarap.net);
• "I tried crepes, I tried pancakes, but I cannot get this thing to get underneath any of my food being cooked without making one big of a mess." (from a customer review on amazon);
• "The company shows immense concern aginst this charge through a post on Instagram, and why won’t they, getting charged from a Trillion Dollar tech giant company is one big of a deal." (from "Apple takes legal action against Prepear — This is why" on www.medium.com);
• "You can also always go with a mt410 then convert the chassis to a ET chassis you'll notice one big of a heck difference." (from www.teknoforums.com);
• "It was one big of a controversy then that led to the breakup of the Sovereign Prince and her French Actress girlfriend Gisèle Pascal after rumors of her being infertile broke out." (from www.theroyalforums.com);
• "Together we fall" is one big of a mess but a very addictive one. I read the three books in a row and I am already craving for more. (from a review of "The Storm We Face (Together We Fall, #3)" by Katie May);
• "Brace yourselves ladies..this is going to be one big of a confession. It's a wrap up of my entire season of football cheer, and the reason why cheerleader was basically ruined for me." (from "Confessions Of A High School Cheerleader" www.fierceboard.com);
• "They usually prefer starting with a marketplace before making the jump to a personalised website. Now moving the entire catalogue from one place to another becomes one big of a task." (from www.wedgecommerce.com).

4. (another adjective after "big") "At any rate, you will see some interesting logical essay topics. To find a topic is yet one significant of a task to do." (from www.forum.malighting.com)