Several having rest disturbed in English county (8)
I believe the answer is:
somerset
'english county' is the definition.
(I've seen this before)
'several having rest disturbed' is the wordplay.
'several' becomes 'some' ('some' can be similar in meaning to 'several').
'having' says to put letters next to each other.
'disturbed' indicates anagramming the letters.
'rest' is an anagram of 'rset'.
'some'+'rset'='SOMERSET'
'in' acts as a link.
(Other definitions for somerset that I've seen before include "Part of UK" , "... and another" , "English county in the West Country" , "Mendip county; a London House" , "western county" .)