Man maybe missing son after joining army, so warlike (7)
I believe the answer is:
hostile
'warlike' is the definition.
(thesaurus)
'man maybe missing son after joining army' is the wordplay.
'man maybe' becomes 'isle' (Isle of Man).
'missing' indicates named letters should be taken away.
'son' becomes 's'.
'after joining' means one lot of letters go next to another.
'army' becomes 'host' (I've seen this before).
'isle' with 's' taken away is 'ile'.
'ile' after 'host' is 'HOSTILE'.
'so' acts as a link.
(Other definitions for hostile that I've seen before include "Aggressive" , "Showing angry opposition" , "Bellicose" , "The soil strangely is unfriendly" , "malevolent" .)