Billions blown in the end protecting fine seaside resort (8)
I believe the answer is:
brighton
'seaside resort' is the definition.
'billions blown in the end protecting fine' is the wordplay.
'billions' becomes 'b' (abbreviation).
'in the end' suggests the final letters.
'protecting' means one lot of letters goes inside another (inserted letters are held or protected).
'fine' becomes 'righto' (both can mean 'yes' or 'alright').
The final letter of 'blown' is 'n'.
'b'+'n'='bn'
'bn' placed around 'righto' is 'BRIGHTON'.
(Other definitions for brighton that I've seen before include "English resort with big thorn" , "East Sussex resort" , "Where the Prince Regent built his Pavilion" , "Sussex coastal resort" , "Graham Greene wrote ` `........ Rock' '" .)