Unstretched? Not any more! (2,6)
I believe the answer is:
no longer
'any more' is the definition.
(synonyms)
'unstretched? not' is the wordplay.
I cannot really understand how this works, but
'not' could be 'no' (negative) and 'no' is found in the answer.
The remaining letters 'longer' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for no longer that I've seen before include "One not disposed to pining" , "a person without yearnings?" , "Someone who doesn't dream" , "Not as formerly" .)