Expert wrong to pick up cards (3,4)
I believe the answer is:
dab hand
'expert' is the definition.
(I've seen this before)
'wrong to pick up cards' is the wordplay.
'wrong' becomes 'bad'.
'to pick up' is a reversal indicator.
'cards' becomes 'hand' (I've seen this in other clues).
'bad' reversed gives 'dab'.
'dab'+'hand'='DAB HAND'
(Other definitions for dab hand that I've seen before include "cursory wash?" , "Past master" , "Barely wash" , "An informal expert such as band had" .)