Regularly concerned with all the Commandments, perhaps (5)
I believe the answer is:
often
'regularly' is the definition.
(I've seen this before)
'concerned with all the commandments perhaps' is the wordplay.
'concerned with' becomes 'of'.
'all the commandments perhaps' becomes 'ten' (Ten Commandments).
'of'+'ten'='OFTEN'
(Other definitions for often that I've seen before include "Frequently, habitually" , "Regularly" , "Frequently, many times" , "Perhaps daily" , "on numerous occasions" .)