Rising volume with air conditioning that makes puss go mad? (6)
I believe the answer is:
catnip
'that makes puss go mad?' is the definition.
'rising volume with air conditioning' is the wordplay.
'rising' is a reversal indicator (going up in a down clue).
'volume' becomes 'pint'.
'with' is a charade indicator (letters next to each other).
'air conditioning' becomes 'ac'.
'pint'+'ac'='pintac'
'pintac' in reverse letter order is 'CATNIP'.
(Other definitions for catnip that I've seen before include "Tin cap (anag.)" , "Plant favoured by felines" , "Plant with scented leaves which felines like" , "treat for kitten" , "Puss would like that" .)