Rural virus, mostly accompanied by stomach pain (7)
I believe the answer is:
bucolic
'rural' is the definition.
(similar in meaning)
'virus mostly accompanied by stomach pain' is the wordplay.
'virus' becomes 'bug'.
'mostly' means to remove the last letter.
'accompanied by' says to put letters next to each other.
'stomach pain' becomes 'colic' (type of stomach complaint).
'bug' with its last letter taken off is 'bu'.
'bu'+'colic'='BUCOLIC'
(Other definitions for bucolic that I've seen before include "Characteristic of country life" , "Pastoral poem" , "Relating to rural life" , "Of rural or pastoral life" , "Rustic - pastoral" .)