Hawk using gas to quell pacifist (6)
I believe the answer is:
neocon
'hawk' is the definition.
(political terms with similar meanings)
'gas to quell pacifist' is the wordplay.
'gas' becomes 'neon' (I've seen this before).
'to quell' is an insertion indicator.
'pacifist' becomes 'co' (conscientious objector).
'neon' going around 'co' is 'NEOCON'.
'using' acts as a link.
(Other definitions for neocon that I've seen before include "Right-winger" , "politician on the right" , "Right-wing American" , "A right winger" , "Someone advocating a new form of democratic capitalism" .)