Old and handsome model (7)
I believe the answer is:
example
'model' is the definition.
(I know that model can be written as example)
'old and handsome' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'and' says to put letters next to each other.
'handsome' becomes 'ample' (handsome can mean ample or plenty).
'ex'+'ample'='EXAMPLE'
(Other definitions for example that I've seen before include "Illustrative case" , "Model - instance" , "Precedent" , "Something to be imitated" , "Instance - pattern" .)