dab hand 
noun British informal
A person who is an expert at a particular activity: Liam is a dab hand at golf...
- I've backed a few horses in my time and I'm a dab hand on the penny falls, but card games are different.
- With the horticulture marquee, floral art marquee and display marquee, there should be something on site to appeal to every visitor, be they a dab hand in the garden or a complete novice.
- The internationally renowned chef at Manchester's acclaimed Chinese restaurant is a dab hand at dealing with woks of boiling oil, and knows all about safety in the kitchen.
Origin
Early 19th century: of unknown origin.
- come to someone's knowledge
- come to terms with
- come to that (or if it comes to that)
- come to think of it
- come true
- come under
- come unglued
- come up
- come up against
- come up against (or hit) a brick wall
- come up dry
- come upon
- come up (or be given) with the rations
- come up (or go down) in the world
- come up (or out) smelling of roses
- comeuppance
- come up roses
- come up smiling
- come up with
- come up with (or deliver) the goods
- come what may
- comfily
- comfiness
- comfit
- comfort