Perimeter captured by embattled general (4)
I believe the answer is:
edge
'perimeter' is the definition.
(I've seen this in another clue)
'captured by embattled general' is the wordplay.
'captured by' indicates the answer is hidden within the clue.
'EDGE' is hidden in the letters of 'embattled general'.
(Other definitions for edge that I've seen before include "Some bordering" , "Rim or slight advantage" , "Rim or sharp side of knife" , "Steal" , "Periphery" .)