Seat, until now, short (4)
I believe the answer is:
sofa
'seat' is the definition.
(sofa is a kind of seat)
'until now short' is the wordplay.
'until now' becomes 'sofar' (both can mean up to the current point).
'short' means to remove the last letter.
'sofar' with its final letter taken off is 'SOFA'.
(Other definitions for sofa that I've seen before include "Settee" , "Chesterfield, maybe" , "Long upholstered seat with back and arms" , "Item of furniture" , "Lounge" .)