N at n
The 'expert' group
These nouns indicate that someone is good or experienced at a particular activity. We include here novice, which indicates that someone is not experienced at a particular activity.
If you're a dab hand at DIY, why not try building a bed on a platform?
The man's an expert at what he does.
The preposition at is sometimes followed by an '-ing' clause.
dab hand expert genius master novice old hand past master whizz wizard
Dickens was a genius at creating characters of great depth and this film is peppered with them.