Support for bad member's stolen weapon (9)
'stolen weapon' is the definition.
'slingshot' can be an answer for 'weapon' (I've seen this before). I am not certain of the 'stolen' bit.
'support for bad member's' is the wordplay.
'support' becomes 'sling' (sling is a type of support for member (ie an arm)).
'for' is a charade indicator (letters next to each other).
'bad member's' becomes 'shot' (I can't justify this - if you can you should give a lot more credence to this answer).
Can you help me to learn more?
(Other definitions for slingshot that I've seen before include "Sing Holst? (Anag)", "fatal to Goliath", "Weapon American kid may produce", "enough to knock you out", "Catapult -- thin gloss (anag)".)