Adversary in Yemen shot (5)
I believe the answer is:
enemy
'adversary' is the definition.
(I know that enemy is a type of adversary)
'yemen shot' is the wordplay.
'shot' is an anagram indicator.
'yemen' with letters rearranged gives 'ENEMY'.
'in' acts as a link.
(Other definitions for enemy that I've seen before include "Foe, adversary" , "Time" , "one in opposition" , "Hostile opponent" , "Hostile person, foe" .)