Always in one version (4)
I believe the answer is:
ever
'always' is the definition.
(synonyms)
'in one version' is the wordplay.
'in' says the answer is hidden in the clue.
'EVER' can be found hidden inside 'one version'.
(Other definitions for ever that I've seen before include "Eternally" , "On any occasion" , "Continuously" , "Always and permanent" , "Possibly" .)