Those people, in short, encountered a tourist in Cornwall (5)
I believe the answer is:
emmet
'a tourist in cornwall' is the definition.
(I've seen this before)
'those people in short encountered' is the wordplay.
'those people in short' becomes 'em' (informal way of saying 'them').
'encountered' becomes 'met' ('meet' can be a synonym of 'encounter').
'em'+'met'='EMMET'
(Other definitions for emmet that I've seen before include "Irish nationalist - archaic ant - Cornish holiday-maker" , "Robert ...., .... Bergin," , "tourist in the South West" , "social worker" , "Irish nationalist, Robert (1778-1803)" .)