River travellers not starting dessert (6)
I believe the answer is:
afters
'dessert' is the definition.
(afters can mean a dessert course)
'river travellers not starting' is the wordplay.
'river travellers' becomes 'rafters' (people travelling with rafts).
'not starting' means to remove the first letter.
'rafters' with its first letter taken off is 'AFTERS'.
(Other definitions for afters that I've seen before include "food for pudding" , "Possibly fools" , "Sweet course" , "Informal desserts may be faster" , "Informal desserts, puddings" .)