Move ruins; they may be pest-ridden (9)

I believe the answer is:

verminous

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

'be pest-ridden' is the definition.
I can't tell whether this definition defines the answer.

'move ruins they' is the wordplay.
'move ruins' anagrams to 'VERMINOUS'.
Though, I am not clear how this is indicated.

'may' is the link.

Can you help me to learn more?

(Other definitions for verminous that I've seen before include "Like fleapit" , "ratty" .)

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

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