The war aside, possibly they still serve (4,7)
I believe the answer is:
'they still serve' is the definition.
The definition suggests an adverb but the answer is not.
'the war aside possibly' is the wordplay.
'possibly' is an anagram indicator.
'thewaraside' is an anagram of 'HEAD WAITERS'.
Can you help me to learn more?
(Another definition for head waiters that I've seen is " Serving men".)