Daughter must leave expensive organ (3)
I believe the answer is:
ear
'organ' is the definition.
(the ear is an organ)
'daughter must leave expensive' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'must leave' is a deletion indicator.
'expensive' becomes 'dear' (similar in meaning).
'dear' with 'd' taken away is 'EAR'.
(Other definitions for ear that I've seen before include "Head of grain" , "Corn seed-holder" , "Lend one and listen" , "Organ of hearing" , "Ability to recognise sounds" .)