Experts in disgrace sometimes (4)
I believe the answer is:
aces
'experts' is the definition.
(ace is a kind of expert)
'in disgrace sometimes' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ACES' is hidden within 'disgrace sometimes'.
(Other definitions for aces that I've seen before include "that are non-returnable" , "Top cards or people" , "Two will make deuce" , "Playing cards with single pips on their faces" , "holes in one" .)