Remote military force returning (3)
I believe the answer is:
far
'remote' is the definition.
(synonyms)
'military force returning' is the wordplay.
'military force' becomes 'RAF' (Royal Air Force).
'returning' says the letters should be written in reverse.
'raf' written backwards gives 'FAR'.
(Other definitions for far that I've seen before include "A long, long way to go" , "Remote" , "Very much" , "At a great distance way" , "Distant" .)