Sweet drink on the rocks? (9)
I believe the answer is:
liquorice
'sweet' is the definition.
(liquorice is a kind of sweet)
'drink on the rocks?' is the wordplay.
'drink' becomes 'liquor' (liquor is a kind of drink**).
'on' means one lot of letters go next to another.
'the rocks?' becomes 'ice' (I've seen this before).
'liquor'+'ice'='LIQUORICE'
(Other definitions for liquorice that I've seen before include "Assortment of sweets sold as a mixture" , "Pontefract cake ingredient" , "Confectionary flavoured with root extract" , "Strange flavour of a Rio clique" , "Plant that's root is used in confectionery" .)