It's at church there's a sensation! (4)
I believe the answer is:
itch
'a sensation' is the definition.
The definition and answer can be both feelings as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'it's at church there's' is the wordplay.
'at' means one lot of letters go next to another.
'church there' becomes 'ch' (abbreviation on maps etc. I am not sure about the 'there' bit.).
'it'+'ch'='ITCH'
Can you help me to learn more?
(Other definitions for itch that I've seen before include "that's irritating" , "longing for something" , "Irritating sensation on skin" , "Seven-yearly desire" , "Burning" .)