Numb clergyman holds editor back (6)
I believe the answer is:
deaden
'numb' is the definition.
(I've seen this before)
'clergyman holds editor back' is the wordplay.
'clergyman' becomes 'dean' (dean is a kind of clergyman).
'holds' means one lot of letters goes inside another.
'editor' becomes 'ed' (abbreviation).
'back' says the letters should be written in reverse.
'ed' back-to-front is 'de'.
'dean' enclosing 'de' is 'DEADEN'.
(Other definitions for deaden that I've seen before include "Kill" , "Damp down; make less sensitive" , "Muffle, deprive of feeling" , "Benumb" , "Take life" .)