Stuffy serials perhaps (7)
I believe the answer is:
airless
'stuffy' is the definition.
(synonyms)
'serials perhaps' is the wordplay.
'perhaps' indicates anagramming the letters.
'serials' with letters rearranged gives 'AIRLESS'.
(Other definitions for airless that I've seen before include "not a breath of wind" , "Unventilated" , "Close" , "Not ventilated" , "Lacking ventilation" .)