Hardly returning ton (3)
I believe the answer is:
not
'hardly' is the definition.
(I've seen this in another clue)
'returning ton' is the wordplay.
'returning' says the letters should be written in reverse.
'ton' backwards is 'NOT'.
(Other definitions for not that I've seen before include "Word of denial" , "In no way, never" , "Type of logic gate" , "Ton (anag.)" , "Negatory word" .)