The vessel got salvaged, then. Cheer up (8)
I believe the answer is:
brighten
'cheer up' is the definition.
(I've seen this before)
'the vessel got salvaged' is the wordplay.
I cannot really see how this works, but
an anagram of 'the' is 'hte' which is within the answer.
'vessel' could be 'brig' (brig is a kind of vessel) and 'brig' is present in the answer.
A single letter 'n' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'then' is the link.
Can you help me to learn more?
(Other definitions for brighten that I've seen before include "Berthing (anag.)" , "Provide illuminations" , "Cheer up; clear up" , "Polish" , "Illuminate, cheer up" .)