Blacken on a grill (4)
I believe the answer is:
'blacken on a grill' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sear that I've seen before include "Burn, scorch intensely" , "Withered" , "Scorch or burn the surface of" , "Dried-up, parched" , "Burn briefly" .)