Also hold out before expert (3,4)
I believe the answer is:
old hand
'expert' is the definition.
(old hand is a kind of expert)
'also hold out before' is the wordplay.
'also' becomes 'and' (both can mean in addition).
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'before' is a charade indicator (letters next to each other).
'hold' is an anagram of 'oldh'.
'and' after 'oldh' is 'OLD HAND'.
(Other definitions for old hand that I've seen before include "master" , "Veteran" , "Experienced performer" , "One's experienced" , "expert?" .)