A supporter acting inappropriately for patriarch (7)
I believe the answer is:
abraham
'for patriarch' is the definition.
(biblical patriarch)
'a supporter acting inappropriately' is the wordplay.
'supporter' becomes 'bra' (a bra gives support to breasts).
'acting inappropriately' becomes 'ham' (I can't explain this - if you can you should believe this answer much more).
'a'+'bra'+'ham'='ABRAHAM'
Can you help me to learn more?
(Other definitions for abraham that I've seen before include "Hebrew patriarch from whom Jews trace descent" , "name" , "Father of all the Jews (7)" , "First patriarch and ancestor of the Hebrews" , "Founder of the Hebrew people" .)