Spoils musical covered by empty numbers (7)
I believe the answer is:
nannies
'spoils' is the definition.
'musical covered by empty numbers' is the wordplay.
'musical' becomes 'annie' (I've seen this before**).
'covered by' means one lot of letters goes inside another.
'empty' means to remove the middle letters.
'numbers' with its centre taken out is 'ns'.
'annie' placed inside 'ns' is 'NANNIES'.
(Other definitions for nannies that I've seen before include "female servants?" , "Female goats" , "nursemaids" , "Children's nurses" , "They look after children" .)