Useless in practice so it ought to be returned (6)
I believe the answer is:
otiose
'useless' is the definition.
(synonyms)
'in practice so it ought to be returned' is the wordplay.
'in' indicates the answer is hidden within the clue.
'to be returned' shows that the letters should be reversed in order (I've seen 'being returned' mean this).
'esoito' is hidden in the letters of 'practice so it ought'.
'esoito' in reverse letter order is 'OTIOSE'.
(Other definitions for otiose that I've seen before include "Redundant, futile" , "Serving no practical purpose" , "Serving no good purpose" , "Lazy, idle" , "Indolent, lazy" .)