old hand 
noun
A person with a lot of experience in something: the examiner is an old hand at the game...
- The biggest problems are felt to come from clashes between out-of-towners and old hands, or between experienced surfers and the novices.
- Perhaps I should instigate a mentoring scheme between old hands and newcomers?
- Mr Cooper said his friend took the lead as he was more experienced at climbing crags since he was an old hand at scaling Stanage Edge in the Peak District.
Synonyms
expert, past master, virtuoso, master, wizard, genius, artist, adept, professional, doyen, veteran, maestro, connoisseur, authority, grandmaster, master hand, skilled person
informal ace, buff, pro, star, whizz, hotshot
British informal dab hand
North American informal maven, crackerjack
- large calorie
- large-cap
- large-eyed
- large gut
- Large Hadron Collider
- large hand
- large-handed
- large-hearted
- large-heartedness
- large intestine
- large leaf
- large-leaved
- large-lung
- large-lunged
- largely
- large-minded
- largemouth
- large-mouthed
- large-mouthed bass
- largen
- largeness
- largeous
- large paper
- large print
- larger than life