Caretaker has month to compose trio (7)
I believe the answer is:
janitor
'caretaker' is the definition.
(I've seen this before)
'month to compose trio' is the wordplay.
'month' becomes 'Jan' (abbreviation for January).
'to compose' indicates an anagram.
'trio' anagrammed gives 'itor'.
'jan'+'itor'='JANITOR'
'has' acts as a link.
(Other definitions for janitor that I've seen before include "Caretaker or doorkeeper" , "Caretaker (mainly US)" , "One employed to clean and maintain a building" , "(In Scotland) school caretaker" , "Person looking after building" .)