Happy and optimistic (6)
I believe the answer is:
cheery
'happy and optimistic' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cheery that I've seen before include "Joyful -- optimistic" , "Merry, jovial" , "Happy, optimistic" , "In good spirits" , "Bright - pleasant - good-humoured" .)