Fill with optimism (6)
I believe the answer is:
uplift
'fill with optimism' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for uplift that I've seen before include "Act of raising" , "Increase; moral elevation" , "Inspire or raise" , "Elevation (of the spirit)" , "Elevate, elate" .)