Aliens can provide a salty solution (6)
I believe the answer is:
saline
'a salty solution' is the definition.
(I've seen this in another clue)
'aliens can' is the wordplay.
'can' is an anagram indicator (I've seen 'canned' mean this (canned can mean drunk)).
'aliens' anagrammed gives 'SALINE'.
'provide' acts as a link.
(Other definitions for saline that I've seen before include "Salty to aliens" , "Salty like sea water" , "Intravenous feeding" , "Containing salt for aliens" , "Like contents of cellar" .)