Last longer than exhausted enemy leader in conflict (7)
I believe the answer is:
outwear
'last longer than' is the definition.
(I've seen this before)
'exhausted enemy leader in conflict' is the wordplay.
'exhausted' becomes 'out' (I've seen this in other clues).
'leader' suggests taking the first letters.
'in' means one lot of letters goes inside another.
'conflict' becomes 'war' (war is a kind of conflict).
The first letter of 'enemy' is 'e'.
'e' placed within 'war' is 'wear'.
'out'+'wear'='OUTWEAR'
(Other definitions for outwear that I've seen before include "Top dressing" , "ride" , "Last longer than others" , "may last longer" , "Drain" .)