Supporter photographed with a catapult (9)
I believe the answer is:
slingshot
'a catapult' is the definition.
('slingshot' can be a synonym of 'catapult')
'supporter photographed' is the wordplay.
'supporter' becomes 'sling' (I am not sure about this - if you are sure you should believe this answer much more).
'photographed' becomes 'shot' ('shoot' can be a synonym of 'photograph').
'sling'+'shot'='SLINGSHOT'
'with' acts as a link.
Can you help me to learn more?
(Other definitions for slingshot that I've seen before include "Sing Holst? (Anag)" , "enough to knock you out" , "that can help you get a stone off" , "fatal to Goliath" , "Catapult -- thin gloss (anag)" .)