Do they take a month to form set groups? (6)
I believe the answer is:
octets
'groups?' is the definition.
The definition and answer can be both groups as well as being plural nouns.
Perhaps you can see an association between them that I don't see?
'do they take a month to form set' is the wordplay.
I cannot quite see how this works, but
'month' could be 'oct' (abbreviation for October) and 'oct' is found in the answer.
an anagram of 'set' is 'ets' which is present in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for octets that I've seen before include "Sets of eight" , "groups of eight, say singers" , "Groups of eight, often singers" , "Groups of eight peformers" .)