Rigid forms of worship (4)

I believe the answer is:

pews

I'm a little stuck... Click here to teach me more about this clue!

'rigid forms' is the definition.
Although both the answer and definition are plural nouns, I can't understand how one could define the other.

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for pews that I've seen before include "Church seating" , "Church benches" , "Church seats" .)

I've seen this clue in The Globe and Mail and The Guardian.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.