Not returning a great deal (3)
I believe the answer is:
'a great deal' is the definition.
'not returning' is the wordplay.
'returning' says the letters should be written in reverse.
'not' reversed gives 'TON'.
(Other definitions for ton that I've seen before include "A slangy 100mph - heavy going" , "High-speed" , "2,240 lbs" , "Unit of weight equivalent to 2240 pounds" , "1000 kilos" .)