Disgusting smell around site (7)
I believe the answer is:
obscene
'disgusting' is the definition.
(obscene can mean disgusting or indecent)
'smell around site' is the wordplay.
'smell' becomes 'B.O.' (informal abbreviation for body odour).
'around' shows that the letters should be reversed in order.
'site' becomes 'scene' (both can mean the location for something).
'bo' back-to-front is 'ob'.
'ob'+'scene'='OBSCENE'
(Other definitions for obscene that I've seen before include "Indecent, lewd" , "repellent" , "unsuitable for children?" , "offending sensibilities?" , "Highly offensive" .)