Monk backed one disliking rockers (3)
I believe the answer is:
mod
'one disliking rockers' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'monk backed' is the wordplay.
'monk' becomes 'dom'.
'backed' shows that the letters should be reversed in order.
'dom' back-to-front is 'MOD'.
Can you help me to learn more?
(Other definitions for mod that I've seen before include "Gaelic literary festival" , "1960s teenager" , "Meeting of the Scottish" , "ministry" , "Rocker's rival?" .)