Man of the cloth's endless compassion over late queen (6)
I believe the answer is:
mercer
'man of the cloth's' is the definition.
(I've seen this before)
'endless compassion over late queen' is the wordplay.
'endless' means to remove the last letter.
'compassion' becomes 'mercy' (mercy is a kind of compassion).
'over' means one lot of letters go next to another (in a down clue, some letters go over others).
'late queen' becomes 'ER' (Elizabeth Regina, ie Queen Elizabeth).
'mercy' with its last letter taken away is 'merc'.
'merc'+'er'='MERCER'
(Other definitions for mercer that I've seen before include "Old tradesman" , "Dealer in textiles or dry goods" , "Dealer in fine cloth" , "Man of the cloth" , "Textile dealer (historical)" .)