Mean no holy man to enter (5)
I believe the answer is:
nasty
'mean' is the definition.
('nasty' can be similar in meaning to 'mean')
'no holy man to enter' is the wordplay.
'no' becomes 'nay' (I've seen this before).
'holy man' becomes 'st'.
'to enter' is an insertion indicator.
'nay' placed around 'st' is 'NASTY'.
(Other definitions for nasty that I've seen before include "Horrid, repugnant" , "Not nice" , "Evil" , "Vile" , "Repulsive" .)