War god in gas makes loving gesture (6)
I believe the answer is:
caress
'loving gesture' is the definition.
(I've seen this in another clue)
'war god in gas' is the wordplay.
'war god' becomes 'ares' (I've seen this before).
'in' means one lot of letters goes inside another.
'gas' becomes 'CS' (short for 2-chlorobenzalmalononitrile).
'ares' inserted within 'cs' is 'CARESS'.
'makes' is the link.
(Other definitions for caress that I've seen before include "Touch with affection" , "Stroke lightly in a loving manner" , "Expression of affection" , "Affectionate stroke" , "Stroke, fondle" .)