In Ireland, a monster pun! (7)

I believe the answer is:

munster

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

'in ireland' is the definition.
(I know that Munster located in the administrative territorial entity Republic of Ireland)

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for munster that I've seen before include "European city" , "Irish quarter?" , "Turns me into a province" , "Irish province or German city" , "Province of Ireland" .)

I've seen this clue in the Evening Standard.

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