Model greeting bishop in doorway perhaps (7)
I believe the answer is:
exhibit
'model' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'greeting bishop in doorway perhaps' is the wordplay.
'greeting' becomes 'hi' (hi is a kind of greeting).
'bishop' becomes 'B' (chess abbreviation).
'in' is an insertion indicator.
'doorway perhaps' becomes 'exit' (I am not sure about this - if you are sure you should believe this answer much more).
'hi'+'b'='hib'
'hib' inserted within 'exit' is 'EXHIBIT'.
Can you help me to learn more?
(Other definitions for exhibit that I've seen before include "Item in show" , "Something shown in public" , "Give public show, as of paintings" , "Publicly display" , "parade" .)