Chapter leaving bishop’s staff more optimistic (6)
I believe the answer is:
rosier
'more optimistic' is the definition.
('rosy' can be similar in meaning to 'optimistic')
'chapter leaving bishop's staff' is the wordplay.
'chapter' becomes 'c' (abbreviation).
'leaving' suggests deleting specific letters.
'bishop's staff' becomes 'crosier' (I've seen this in another clue).
'crosier' with 'c' taken away is 'ROSIER'.
(Other definitions for rosier that I've seen before include "Brighter" , "looking more healthy" , "More fortunate or hopeful" .)