Amorous old drunk's high (10)
I believe the answer is:
malodorous
'high' is the definition.
(both can mean very smelly)
'amorous old drunk's' is the wordplay.
'drunk's' indicates an anagram (I've seen 'drunk' mean this).
'amorous'+'old'='amorousold'
'amorousold' with letters rearranged gives 'MALODOROUS'.
(Other definitions for malodorous that I've seen before include "Foul-smelling" , "Having a bad smell" , "Smelling very unpleasant" .)