Clergyman is able to get about (5)
I believe the answer is:
canon
'clergyman' is the definition.
(type of clergyman)
'able to get about' is the wordplay.
'able' becomes 'can'.
'to get' is a charade indicator (letters next to each other).
'about' becomes 'on' (as in a book 'on' a certain topic).
'can'+'on'='CANON'
'is' acts as a link.
(Other definitions for canon that I've seen before include "Body of works" , "Round, general rule" , "Cathedral cleric" , "General principle; musical round" , "Basic law or principle" .)