English county on the North Sea (5)
I believe the answer is:
essex
'english county on the north sea' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for essex that I've seen before include "Favourite of Elizabeth I" , "County NE of London" , "County east of London" , "County, its tasteless moneyed Man" , "Chelmsford's county" .)