Crossword Genius

They provide cover in certain empty rooms (8)

Ross

I believe the answer is:

insurers

'they provide cover' is the definition.

'in certain empty rooms' is the wordplay.
'certain' becomes 'sure' ('sure' can be a synonym of 'certain').
'empty' says to hollow out the word (remove centre letters).
'rooms' with its centre taken out is 'rs'.
'in'+'sure'+'rs'='INSURERS'

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