Dishearten loser I made drunk (10)
I believe the answer is:
demoralise
'dishearten' is the definition.
('dishearten'->'demoralize' is in my internal thesaurus and 'ize'->'ise')
'loser i made drunk' is the wordplay.
'drunk' indicates anagramming the letters.
'loser'+'i'+'made'='loserimade'
'loserimade' with letters rearranged gives 'DEMORALISE'.
(Other definitions for demoralise that I've seen before include "Cause to lose confidence/hope" , "Make downhearted" , "Cause to lose confidence" , "Throw into confusion" , "Crush" .)