Content leaving employment after month in music group (5)
I believe the answer is:
octet
'music group' is the definition.
(group of eight musicians)
'content leaving employment after month' is the wordplay.
'content leaving' means to remove the middle letters (the word's contents are removed).
'after' says to put letters next to each other.
'month' becomes 'Oct' (abbreviation for October).
'employment' with its centre taken out is 'et'.
'et' put after 'oct' is 'OCTET'.
'in' is the link.
(Other definitions for octet that I've seen before include "Eight people together" , "Music for eight" , "Work for eight players" , "Group of eight musicians" , "Group of eight players" .)