Bright church strangely frightening (6)
I believe the answer is:
cheery
'bright' is the definition.
(I've seen this in another clue)
'church strangely frightening' is the wordplay.
'church' becomes 'ch' (common abbreviation).
'strangely frightening' becomes 'eery' (I've seen this before).
'ch'+'eery'='CHEERY'
(Other definitions for cheery that I've seen before include "Merry, jovial" , "Bright - pleasant - good-humoured" , "Happy, optimistic" , "Joyful -- optimistic" , "In good spirits" .)