Definitions:

1. Often used in reference to practical tasks, crafts or hobbies where the person has developed notable skill. NOUN
   • He's a dab hand at fixing cars, so we always go to him when our vehicles need repairs.
2. Someone who is very good or experienced at something, often due to practice or natural talent. NOUN
   • She's a dab hand at painting, her artwork is always impressive.

Synonyms:

• ace
• expert
• skilled worker
• whiz