Made bus boil to take upstart on board drunk (8)
I believe the answer is:
bibulous
'drunk' is the definition.
(synonyms)
'made bus boil to take upstart on board' is the wordplay.
'made' indicates an anagram.
'to take' is a charade indicator (letters next to each other).
'upstart' becomes 'u' (start of the word 'up').
'on board' is an insertion indicator.
'bus'+'boil'='busboil'
'busboil' is an anagram of 'bibulos'.
'bibulos' going around 'u' is 'BIBULOUS'.
(Other definitions for bibulous that I've seen before include "as boozers" , "Addicted to alcohol" , "Excessively fond of drink" , "Addicted to 20" , "Fond of booze" .)