On time, peers one knocks off perch, say (6)
I believe the answer is:
priest
'one knocks off perch say' is the definition.
(tool used to kill fish)
'on time peers' is the wordplay.
'on' says to put letters next to each other.
'time' becomes 't'.
'peers' becomes 'pries'.
't' after 'pries' is 'PRIEST'.
(Other definitions for priest that I've seen before include "Professional woman perhaps" , "Stripe for a cleric" , "Clergyman" , "Father" , "person of religion" .)