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' (cash is a type of money).
'left' becomes 'l' (common abbreviation).
'in' means one lot of letters goes inside another.
'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" .)