Bounty -- big ship ending in catastrophe (8)
I believe the answer is:
largesse
'bounty' is the definition.
(I've seen this before)
'big ship ending in catastrophe' is the wordplay.
'big' becomes 'large' (synonyms).
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'ending in' indicates one should take the final letters.
The final letter of 'catastrophe' is 'e'.
'large'+'ss'+'e'='LARGESSE'
(Other definitions for largesse that I've seen before include "Liberal gift" , "Magnanimous bestowal of gifts" , "Generosity in bestowing gifts" , "Magnanimity, munificence" , "Money or gifts generously given" .)