Music-maker's raincoat shortly getting tailored (7)
I believe the answer is:
ocarina
'music-maker's' is the definition.
(ocarina is a type of wind instrument)
'raincoat shortly getting tailored' is the wordplay.
'shortly' means to remove the last letter.
'getting tailored' is an anagram indicator (the letters are customised ).
'raincoat' with its last letter taken off is 'raincoa'.
'raincoa' is an anagram of 'OCARINA'.
(Other definitions for ocarina that I've seen before include "music-maker" , "Bird-shaped flute" , "Terracotta wind instr." , "Inca oar made into a musical instrument" , "Toy flute" .)