That fellow travels around British Isles (8)
I believe the answer is:
hebrides
'isles' is the definition.
(I've seen this before)
'that fellow travels around british' is the wordplay.
'that fellow' becomes 'he' ('he' refers to a man).
'travels' becomes 'rides' (riding is a kind of traveling).
'around' is an insertion indicator.
'british' becomes 'b' (abbreviation e.g. in BBC).
'he'+'rides'='herides'
'herides' going around 'b' is 'HEBRIDES'.
(Other definitions for hebrides that I've seen before include "Shipping Forecast area" , "Strangely, his breed comes from Scottish archipelago" , "His breed comes from west of Scotland" , "Scottish islands" , "overture" .)