Builder regularly ignored bad knee in his address (5)
I believe the answer is:
maker
'builder' is the definition.
(thesaurus)
'regularly ignored bad knee in his address' is the wordplay.
'regularly ignored' means one should take alternating letters.
'in' is an insertion indicator.
'his address' becomes 'mr' (form of address for a man).
'bad'+'knee'='badknee'
The alternate letters of 'badknee' are 'ake'.
'ake' going within 'mr' is 'MAKER'.
(Other definitions for maker that I've seen before include "Fabricator; poet (arch.)" , "Creator" , "Producer" , "Manufacturer" , "God Almighty" .)