Just rewards — puddings. by the sound of it (7)
I believe the answer is:
deserts
'just rewards' is the definition.
('just deserts' can mean what someone deserves)
'puddings by the sound of it' is the wordplay.
'puddings' becomes 'desserts' (I've seen this before).
'by the sound of it' shows a homophone (sound like).
'desserts' sounds like 'DESERTS'.
(Other definitions for deserts that I've seen before include "Sahara and Gobi" , "Wastes" , "Kalahari and Gobi" , "parts of Africa" , "Abandons; barren places" .)