Money left in conflict (5)
I believe the answer is:
clash
'conflict' is the definition.
(clashing is a kind of conflicting)
'money left in' is the wordplay.
'money' becomes 'cash' (I've seen this before).
'left' becomes 'l' (common abbreviation).
'in' is an insertion indicator.
'cash' enclosing 'l' is 'CLASH'.
(Other definitions for clash that I've seen before include "Loud noise - conflict" , "Collision (of colour)" , "Conflict, between colours say" , "Conflict; be incompatible" , "Disagree violently" .)