Drunk, pa's despair vanishes (10)
I believe the answer is:
disappears
'vanishes' is the definition.
('disappear' can be a synonym of 'vanish')
'drunk pa's despair' is the wordplay.
'drunk' indicates anagramming the letters.
'pas'+'despair'='pasdespair'
'pasdespair' with letters rearranged gives 'DISAPPEARS'.
(Other definitions for disappears that I've seen before include "becomes lost" , "goes missing" .)