Cleric, comparatively dull one perhaps (8,6)
I believe the answer is:
cardinal number
'one perhaps' is the definition.
(one is a cardinal number)
'cleric comparatively dull' is the wordplay.
'cleric' becomes 'cardinal' (I've seen this before).
'comparatively dull' becomes 'number' (more numb or dulled).
'cardinal'+'number'='CARDINAL NUMBER'
(Other definitions for cardinal number that I've seen before include "E.g. one" , "For instance, one" , "Maybe one" , "one, perhaps" , "It could be one" .)