It’s accepted by two US cities as a form of prayer (6)
I believe the answer is:
litany
'a form of prayer' is the definition.
(I've seen this before)
'it's accepted by two us cities as' is the wordplay.
I cannot quite see how this works, but
'accepted' could be 'a' (financial abbreviation) and 'a' is found within the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
'as' could be 'in' (I've seen this in other clues) and 'in' is found within the leftover letters.
This explanation may well be incorrect...
(Other definitions for litany that I've seen before include "Repeated prayers" , "Succession of requests" , "Long and tedious list" , "Long and tedious series" , "Tedious speech" .)