Quite happy with a rented piano (7)
I believe the answer is:
'piano' is the definition.
Both the definition and answer are adjectives. Maybe you can see an association between them that I don't see?
'quite happy with a rented' is the wordplay.
'quite happy' becomes 'p' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'with' is a charade indicator (letters next to each other).
'a rented' becomes 'leased' (I've seen this before).
Can you help me to learn more?
(Other definitions for pleased that I've seen before include "Glad", "Gratified", "like Punch?", "Happy, satisfied", "Content".)