Leading article — six Times rejected (5)
I believe the answer is:
ahead
'leading' is the definition.
('ahead' can be a synonym of 'leading')
'article six times rejected' is the wordplay.
'article' becomes 'a' (indefinite article).
'six' becomes 'hexad' ('hexad' can be a synonym of 'six').
'times' becomes 'x' (multiplication sign).
'rejected' indicates named letters should be taken away.
'hexad' with 'x' taken away is 'head'.
'a'+'head'='AHEAD'
(Other definitions for ahead that I've seen before include "at pole" , "in van" , "What's down the road" , "likely to win?" , "In the future" .)