dab hand

Từ điển Oxford Advanced Learner 8th

ˌdab ˈhand [dab hand dab hands] BrE NAmE noun (BrE, informal)
a person who is very good at doing sth or using sth
•He's a dab hand at cooking spaghetti.
•She's a dab hand with a paintbrush.

Word Origin:
early 19th cent.: of unknown origin.