Small, mischievous creature at church event in sort of restaurant? (4-7)
I believe the answer is:
self-service
'sort of restaurant?' is the definition.
(restaurant where diners serve themselves)
'small mischievous creature at church event' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'mischievous creature' becomes 'elf' (creature in folk lore).
'at' means one lot of letters go next to another.
'church event' becomes 'service' (a church service).
's'+'elf'+'service'='SELF-SERVICE'
'in' acts as a link.
(Other definitions for self-service that I've seen before include "Like some shops or cafeterias" , "Like some restaurants" , "Without waiting, take" .)