Long version finally appearing after twelve months (5)
I believe the answer is:
yearn
'long' is the definition.
(I know that long can be written as yearn)
'version finally appearing after twelve months' is the wordplay.
'finally' indicates one should take the final letters.
'appearing after' is a charade indicator (letters next to each other).
'twelve months' becomes 'year' (I've seen this in another clue).
The last letter of 'version' is 'n'.
'n' put after 'year' is 'YEARN'.
(Other definitions for yearn that I've seen before include "Ache, crave" , "Pant - pine" , "wish" , "lust" , "Long - pine" .)