The phrase "a definite idea of" is grammatically correct and can be used in written English.
It is typically used to indicate a clear or specific understanding or concept of something. Example: "After reading the article, I now have a definite idea of the author's perspective on the topic."
He has a definite idea of what he's doing.
Lily A At 15, I'm sure your son has a definite idea of his image and probably isn't easily cajoled into wearing just anything.
Clinton Leeks, from HS2, said he understood the "frustration" of the villagers about not having a definite idea of what was happening to their homes.
Despite Soros' loud contentions that the rich should pay their "fair" share, it's clear that he has a definite idea of what's fair and it doesn't include paying taxes conventionally.
Being a relatively small woman of Asian heritage, people a have a definite idea of who I am supposed to be before they know anything about me.
When Jam and Lewis first started working with Carey, they did not have a definite idea of what Carey expected from them.
Should the Lakers lose Saturday in Game 7 of their first-round series against the Denver Nuggets, Magic Johnson has a definite idea on what will happen next.
By these actions the investor revealed that he (most of the investors were men) had a definite idea about the future of two stocks: he expected the stock that he bought to do better than the one he sold.
You have to have a very definite idea of what you're doing or it's too late to change".
According to Wild, the whole thing could be chalked up to sour grapes on Ocean's part: "Frank had a very definite idea of exactly what he wanted to do and how he wanted to do it.
Since an agent engaged in deliberation has no definite idea of what to decide, or of what a good decision will look like, it is unclear how agents can be thought to exercise direct control over their decisions.
