Sweet seeing wrinkle on old model (7)
I believe the answer is:
truffle
'sweet' is the definition.
(truffle is a kind of sweet)
'wrinkle on old model' is the wordplay.
I cannot really understand how this works, but
'model' could be 't' (Ford Model T car) and 't' is located in the answer.
The remaining letters 'ruffle' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'seeing' acts as a link.
Can you help me to learn more?
(Other definitions for truffle that I've seen before include "Rich food" , "Sweet - edible fungus growing underground" , "Edible fungus -- chocolate sweet" , "Fungoid delicacy" , "Witty remark" .)