a/one hell of a...
hell of a
1. Quite good or impressive. That was one hell of a party you threw for Kelly. Everyone said they had such a great time. He's a hell of a ballplayer. I wouldn't be surprised if he made it to the pros someday.
2. Very difficult. I had a hell of a time trying to change the flat tire. The lug nuts didn't want to budge.
a hell of a someone or somethingand a helluva someone or something
1. Inf. a very bad person or thing. (Use caution with hell.) That's a hell of a way to treat someone. He's a hell of a driver! Watch out! 2. Inf. a very good person or thing. (Use caution with hell.) He is one hell of a guy. We really like him. We had a helluva good time.
hell of a
Also, one hell of a
1. See devil of a.
2. This phrase is used as an intensive to emphasize certain qualities about the noun it modifies. By itself the idiom is ambiguous, for its exact meaning depends on the context. For example, He is a hell of a driver can mean either that he is very skillful or that he is a terrible driver. Similarly, We had one hell of a time can mean either that we enjoyed ourselves greatly or that we had an awful or difficult time. [Second half of 1700s]
a (or one) hell of a —used to emphasize something very bad or great. informal
1990 Stephen King The Stand If someone on the committee has been leaking, we're in a hell of a jam.
a/one hell of a...(spoken, slang) somebody/something that is very bad, good, unusual, impressive, etc: We had a hell of a good time at the night club. ♢ I had one hell of a hangover the next morning.
This is sometimes written as ‘a/one helluva’.