Save a French takeaway (6)
I believe the answer is:
unless
'save' is the definition.
(I've seen this in another clue)
'a french takeaway' is the wordplay.
'a french' becomes 'un' ('a' in French).
'takeaway' becomes 'less' (I've seen this in other clues).
'un'+'less'='UNLESS'
(Other definitions for unless that I've seen before include "Conjunction meaning except when" , "Conditional on" , "Except on the condition that" , "Though" , "Except, save" .)