Hot refreshment in mug during church function (9)
I believe the answer is:
casserole
'hot refreshment' is the definition.
'mug during church function' is the wordplay.
I cannot quite understand how this works, but
'mug' could be 'ass' (I've seen this before) and 'ass' is found within the answer.
'church' could be 'ce' (abbreviation for Church of England) and 'ce' is found in the leftover letters.
'function' could be 'role' ('role' can be a synonym of 'function') and 'role' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'in' acts as a link.
(Other definitions for casserole that I've seen before include "Oven dish" , "Kind of stew" , "Stew-pan" , "Stew; dish" , "meal" .)