Tympanic membrane (7)
I believe the answer is:
eardrum
'tympanic membrane' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for eardrum that I've seen before include "Rude ram (anag.)" , "Ear membrane" , "Vibrating membrane in the head" , "Auditory membrane" , "Aural membrane" .)