Hostile force in Yemen beaten (5)
I believe the answer is:
enemy
'hostile force' is the definition.
(I've seen this in another clue)
'yemen beaten' is the wordplay.
'beaten' indicates an anagram (letters beaten up or destroyed).
'yemen' anagrammed gives 'ENEMY'.
'in' acts as a link.
(Other definitions for enemy that I've seen before include "is against us" , "one in opposition" , "other side (like 16)" , "Foe, adversary" , "Yemen (anag.)" .)