Worshipper's place in which food eaten, primarily? (9)
I believe the answer is:
refectory
'worshipper's place' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'in which food eaten primarily?' is the wordplay.
'in' means one lot of letters goes inside another.
'which' becomes 'rectory' (I can't justify this - if you can you should give a lot more credence to this answer).
'primarily?' indicates taking the first letters (I've seen 'primarily' mean this).
The first letters of 'food eaten' is 'fe'.
'rectory' enclosing 'fe' is 'REFECTORY'.
(Other definitions for refectory that I've seen before include "Communal dining room" , "Communal dining-hall" , "Communal room for meals" , "Communal dining hall" , "dining area" .)