Sulphur and oxygen no good for the air (4)
I believe the answer is:
song
'the air' is the definition.
(thesaurus)
'sulphur and oxygen no good' is the wordplay.
'sulphur' becomes 's' ('S' can be a synonym of 'sulphur').
'and' says to put letters next to each other.
'oxygen' becomes 'o' (atomic symbol for oxygen).
'no' becomes 'n' (common abbreviation).
'good' becomes 'g' (abbreviation).
's'+'o'+'n'+'g'='SONG'
'for' is the link.
(Other definitions for song that I've seen before include "Something recorded by 26 [FACES] , for example" , "Musical rendition" , "Vocal number" , "Piece of vocal music" , "Unnecessary fuss" .)