Counterfoils found in the ashtray (5)
I believe the answer is:
stubs
'counterfoils' is the definition.
('stub' can be a synonym of 'counterfoil')
'the ashtray' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
The remaining letters 'subs' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'found in' is the link.
Can you help me to learn more?
(Other definitions for stubs that I've seen before include "Butts" , "residual pieces" .)