Oddly, finer dress stores maintain no returns policy (7,7)
I believe the answer is:
finders keepers
'oddly finer dress stores' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'maintain no returns policy' is the wordplay.
I cannot really see how this works, but
'maintain' could be 'keep' (synonyms) and 'keep' is found in the answer.
'no' could be 'n' (common abbreviation y/n) and 'n' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for finders keepers that I've seen is " Justification for holding on to something discovered".)