Pulsating laser is close (7)

I believe the answer is:

airless

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'close' is the definition.
(synonyms)

'pulsating laser is' is the wordplay.
'laser is' can be anagrammed to 'AIRLESS'.
But, I am not clear how this is indicated.

Can you help me to learn more?

(Other definitions for airless that I've seen before include "Close" , "Very stuffy" , "Not ventilated" , "Lacking ventilation" , "Unventilated" .)

I've seen this clue in The Sun.

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