Clan constituent missed the start for the month (9)
I believe the answer is:
september
'the month' is the definition.
(September is an example)
'clan constituent missed the start' is the wordplay.
'clan' becomes 'sept' (division of family).
'constituent' becomes 'member' (I've seen this in another clue).
'missed the start' means to remove the first letter.
'member' with its first letter taken off is 'ember'.
'sept'+'ember'='SEPTEMBER'
'for' is the link.
(Other definitions for september that I've seen before include "about 4 weeks" , "It follows 3" , "Last month" , "Ninth month" , "The longest month?" .)