Wartime partners (6)
I believe the answer is:
allies
'wartime partners' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for allies that I've seen before include "'Friendly, helpful nations (6)'" , "They join together as in war" , "WW2 victors" , "They are banded together for mutual support" , "Friends who band together" .)