Weapons from Mars, perhaps (4)
I believe the answer is:
arms
'weapons' is the definition.
('arm' can be a synonym of 'weapon')
'mars perhaps' is the wordplay.
'perhaps' indicates anagramming the letters.
'mars' anagrammed gives 'ARMS'.
'from' is the link.
(Other definitions for arms that I've seen before include "See 11" , "Arsenal's items?" , "Members" , "Provides with weapons" , "you'll find in the gunroom" .)