The upper chamber of the heart (7)
I believe the answer is:
auricle
'the upper chamber of the heart' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for auricle that I've seen before include "atrium" , "External part of the ear" , "place in one's heart" , "Something of a heart" , "Air clue for part of the ear" .)