Give ear to piano in advertisement (4)
I believe the answer is:
plug
'advertisement' is the definition.
(a plug is an advert for something)
'give ear to piano' is the wordplay.
I cannot really understand how this works, but
'ear' could be 'lug' (informal term for an ear) and 'lug' is found in the answer.
'piano' could be 'p' (musical abbreviation) and 'p' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for plug that I've seen before include "Blatant promotion" , "Piece of tobacco; block" , "Cork" , "Stopper - advertisement" , "Mention favourably - stopper" .)