Popular Welsh girl entertaining accomplished islander (10)
I believe the answer is:
indonesian
'islander' is the definition.
(Indonesia is a made up thousands of islands)
'popular welsh girl entertaining accomplished' is the wordplay.
'popular' becomes 'in'.
'welsh girl' becomes 'sian' (common Welsh name).
'entertaining' indicates putting letters inside.
'accomplished' becomes 'done' (I've seen this before).
'in'+'sian'='insian'
'insian' going around 'done' is 'INDONESIAN'.
(Other definitions for indonesian that I've seen before include "Asian" , "Australian neighbour" .)