Main sentence identifying cormorant, for example (7)
I believe the answer is:
seabird
'cormorant for example' is the definition.
(cormorant is a kind of seabird)
'main sentence' is the wordplay.
'main' becomes 'sea' (the main is an old name for the sea).
'sentence' becomes 'bird' (slang term for a prison sentence).
'sea'+'bird'='SEABIRD'
'identifying' is the link.
(Other definitions for seabird that I've seen before include "gannet, perhaps" , "Gull, for example" , "Marine creature" , "A gull, for instance" , "gull, say" .)