Rather entertaining church glass (8)
I believe the answer is:
schooner
'glass' is the definition.
(I know that schooner is a type of glass)
'rather entertaining church' is the wordplay.
'rather' becomes 'sooner' ('I'd sooner do that' means 'I'd rather do that').
'entertaining' means one lot of letters goes inside another (inviting in, as for dinner).
'church' becomes 'ch' (abbreviation on maps etc).
'sooner' placed around 'ch' is 'SCHOONER'.
(Other definitions for schooner that I've seen before include "Large beer or sherry glass" , "Swift sailing vessel - sherry glass" , "Old sailing ship and tall sherry glass" , "A measure or glass for sherry" , "Measure for sherry or kind of sailing ship" .)