The day before (3)
'the day before' is the definition.
(eve is the night before something)
This is all the clue.
(Other definitions for eve that I've seen before include "'All About - - ' (Bette Davis film)" , "Day before a festival" , "Day before; girl's name" , "One from Genesis" , "She reportedly lived first" .)
'the day before' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for yesterday that I've seen before include "Recent time" , "Beatles' song" , "Lennon and McCartney classic" , "Beatles hit - Thursday" , "Tue" .)