To cause dampness is ruinous to mines (7)

I believe the answer is:

moisten

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'to cause dampness' is the definition.
I can't judge whether this definition defines the answer.

'ruinous to mines' is the wordplay.
'ruinous' is an anagram indicator.
'to'+'mines'='tomines'
'tomines' with letters rearranged gives 'MOISTEN'.

'is' is the link.

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(Other definitions for moisten that I've seen before include "Add water - dampen" , "Make damp or slightly wet" , "contrary to sixteen down [DEHYDRATE]!" , "It's on me (anag)" , "Make damp, say lips with tongue" .)

I've seen this clue in The Irish Independent.

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