Fail to be excited for rescue vessel (8)
I believe the answer is:
lifeboat
'for rescue vessel' is the definition.
(boat which rescues people)
'fail to be excited' is the wordplay.
'excited' indicates an anagram.
'fail'+'to'+'be'='failtobe'
'failtobe' is an anagram of 'LIFEBOAT'.
(Other definitions for lifeboat that I've seen before include "It's used to rescue people at sea" , "I bet loaf on maritime rescue vessel" , "To fable I turn if in danger of sinking" , "saver, in the main" , "Vessel to rescue people at sea" .)