It's futile going back in time, so it often appears (6)
I believe the answer is:
otiose
'it's futile' is the definition.
(synonyms)
'going back in time so it often appears' is the wordplay.
'going back' is a reversal indicator.
'in' indicates a hidden word.
'esoito' is hidden in the letters of 'time so it often appears'.
'esoito' reversed gives 'OTIOSE'.
(Other definitions for otiose that I've seen before include "Serving no useful purpose" , "Slothful" , "Without practical purpose" , "Lazy, idle" , "Disinclined to work or exert oneself" .)