Conflict lets US mobilise (6)
I believe the answer is:
tussle
'conflict' is the definition.
(I know that tussle is a type of combat)
'lets us mobilise' is the wordplay.
'mobilise' is an anagram indicator (I've seen 'mobilising' mean this).
'lets'+'us'='letsus'
'letsus' is an anagram of 'TUSSLE'.
(Other definitions for tussle that I've seen before include "scrap" , "Struggle like wrestling bout" , "Sharp struggle" , "'Physical fight, struggle (6)'" , "Wrestle, scuffle" .)