Agitate dry salesman from the south (7)
I believe the answer is:
perturb
'agitate' is the definition.
(thesaurus)
'dry salesman from the south' is the wordplay.
'dry' becomes 'brut' (type of wine).
'salesman' becomes 'rep' (I've seen this before).
'from the south' says the letters should be written backwards (in a down clue, letters go up).
'brut'+'rep'='brutrep'
'brutrep' backwards is 'PERTURB'.
(Other definitions for perturb that I've seen before include "Disturb - trouble" , "Bother" , "Disturb greatly" , "Unsettle; PR brute (anag.)" , "Disturb the composure of" .)