Alleged to include a supporter? (3)
I believe the answer is:
leg
'a supporter?' is the definition.
(I've seen this in another clue)
'alleged to include' is the wordplay.
'to include' says the answer is hidden in the clue.
'LEG' is hidden within 'alleged'.
(Other definitions for leg that I've seen before include "Gigot" , "Run < on" , "Member" , "Projecting support for chair or table" , "Stage (of race)" .)