Best comedian, half-ignored, left previously (8)
I believe the answer is:
overcome
'best' is the definition.
(I've seen this before)
'comedian half-ignored left previously' is the wordplay.
'half ignored' means to take half the letters.
'left' becomes 'over' (I've seen this before).
'previously' says to put letters next to each other.
'comedian' cut in half is 'come'.
'come' after 'over' is 'OVERCOME'.
(Other definitions for overcome that I've seen before include "Overwhelm (someone)" , "Vanquish" , "Defeat (someone)" , "Wiped the floor with" , "Defeat, conquer" .)