Patriarch putting an undergarment over back of thigh (7)
I believe the answer is:
abraham
'patriarch' is the definition.
(biblical patriarch)
'an undergarment over back of thigh' is the wordplay.
'an' becomes 'a'.
'undergarment' becomes 'bra' (bra is a kind of undergarment).
'over' is a charade indicator (letters next to each other).
'back of thigh' becomes 'ham' (ham can mean the back of a thigh).
'a'+'bra'+'ham'='ABRAHAM'
'putting' is the link.
(Other definitions for abraham that I've seen before include "- Lincoln, US president" , "Founder of the Hebrew people" , "Isaac's father" , "OT Hebrew patriarch" , "relative of 18 [REBECCA]" .)