Frustrated Caledonian goes to church with editor (8)
I believe the answer is:
scotched
'frustrated' is the definition.
('scotch' can be a synonym of 'frustrate')
'caledonian goes to church with editor' is the wordplay.
'caledonian' becomes 'Scot' (Caledonia was the Latin name for Scotland).
'goes to' says to put letters next to each other.
'church' becomes 'ch' (abbreviation on maps etc).
'with' means one lot of letters go next to another.
'editor' becomes 'ed' (abbreviation).
'scot'+'ch'+'ed'='SCOTCHED'
(Other definitions for scotched that I've seen before include "Frustrated" , "Put the lid on" .)