With belt, punisher regularly lashed Catholic swinger! (8)
I believe the answer is:
thurible
'catholic swinger' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'with belt punisher regularly lashed' is the wordplay.
'with' says to put letters next to each other.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'lashed' is an anagram indicator.
The alternating letters of 'punisher' are 'uihr'.
'belt' put next to 'uihr' is 'beltuihr'.
'beltuihr' anagrammed gives 'THURIBLE'.
Can you help me to learn more?
(Other definitions for thurible that I've seen before include "Container for burning incense in a religious ritual" , "Censer" , "Container on a chain for burning incense" .)