Holy man had us converted (5)
I believe the answer is:
sadhu
'holy man' is the definition.
(I've seen this before)
'had us converted' is the wordplay.
'converted' indicates an anagram.
'had'+'us'='hadus'
'hadus' anagrammed gives 'SADHU'.
(Other definitions for sadhu that I've seen before include "Indian wandering holy man" , "Indian holy man or sage" , "Hindu wandering holy man" , "Ascetic" , "one choosing austerity" .)