One side of paper clergyman does not finish (5)
I believe the answer is:
recto
'one side of paper' is the definition.
(I've seen this before)
'clergyman does not finish' is the wordplay.
'clergyman does' becomes 'rect' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'not' becomes 'no' (negative).
'finish' suggests halving the letters.
'no' cut in half is 'o'.
'rect'+'o'='RECTO'
(Other definitions for recto that I've seen before include "front of leaf" , "Side of paper" , "one side" , "front page" , "right page" .)