Catholic building in wet field went with the flow, mopping up rug (6,6)

I believe the answer is:

paddys wigwam

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

'catholic building' is the definition.
(nickname for Liverpool's Metropolitan Cathedral)

'wet field went with the flow mopping up rug' is the wordplay.
'wet field' becomes 'paddy' (paddy is a kind of field. I am not sure about the 'wet' bit.).
'went with the flow' becomes 'swam' (went with the flow of water).
'mopping up' indicates putting letters inside (mop up can mean to eat or consume).
'rug' becomes 'wig' ('rug' is an informal term for a wig).
'swam' going around 'wig' is 'swigwam'.
'paddy'+'swigwam'='PADDYS WIGWAM'

'in' acts as a link.

Can you help me to learn more?

I've seen this clue in 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.