Priest perhaps secure in St. James's area (8)
I believe the answer is:
clubland
'priest' is the definition.
Both the answer and definition are singular nouns.
Maybe there's an association between them I don't understand?
'secure in st james's area' is the wordplay.
'secure in st james's' becomes 'club' (I can't explain this - if you can you should believe this answer much more).
'area' becomes 'land area' (land area is a kind of area).
'club'+'land'='CLUBLAND'
'perhaps' is the link.
Can you help me to learn more?
(Other definitions for clubland that I've seen before include "It tends to be busy on Saturday night" , "Area with lots of night spots" , "Social area of St James's" .)