Specimen from partner that was large (7)
I believe the answer is:
example
'specimen' is the definition.
(I know that specimen can be written as example)
'partner that was large' is the wordplay.
'partner that was' becomes 'ex' (an ex-partner).
'large' becomes 'ample' (similar in meaning).
'ex'+'ample'='EXAMPLE'
'from' acts as a link.
(Other definitions for example that I've seen before include "Illustrative case" , "Punishment" , "Model - instance" , "Typical specimen" , "warning" .)