Matching wits with some solvers, usually (6)
I believe the answer is:
versus
'matching wits with' is the definition.
(as in opposing in a battle of wits)
'some solvers usually' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'VERSUS' is hidden within 'solvers usually'.
(Other definitions for versus that I've seen before include "Against in games" , "Preposition meaning against, as in contest" , "v. (sport)" , "playing" , "taking part in team sports" .)