Plonk racket in Riviera on ground (3,9)
I believe the answer is:
vin ordinaire
'plonk' is the definition.
(both can mean cheap wine)
'racket in riviera on ground' is the wordplay.
'racket' becomes 'din' (I've seen this before).
'in' means one lot of letters goes inside another.
'ground' indicates an anagram ('grind' the letters into a new form).
'riviera'+'on'='rivieraon'
'rivieraon' with letters rearranged gives 'vinoraire'.
'din' placed within 'vinoraire' is 'VIN ORDINAIRE'.
(Other definitions for vin ordinaire that I've seen before include "this isn't the best drink" , "Plonk" , "Cheap table wine" .)