Islander cheers Welsh girl entertaining crew (9)
I believe the answer is:
tasmanian
'islander' is the definition.
(someone from Tasmania)
I cannot understand how the rest of the clue works.
(Other definitions for tasmanian that I've seen before include "Islander" , "Ferocious Australian marsupial" , "Aussie statesman" , "From one Australian state" , "of island" .)