Evil one Lionel disheartened (3)
I believe the answer is:
ill
'evil' is the definition.
(as in doing people ill)
'one lionel disheartened' is the wordplay.
'one' becomes 'i' (Roman numeral).
'disheartened' says to hollow out the word (remove centre letters) (the middle or heart is removed).
'lionel' with its middle taken out is 'll'.
'i'+'ll'='ILL'
(Other definitions for ill that I've seen before include "state of America" , "Evil or sick" , "Badly diminished" , "Misfortune" , "Where to find Chicago" .)