Left on the day before, taking a break (5)
I believe the answer is:
leave
'break' is the definition.
(I've seen this before)
'left on the day before taking a' is the wordplay.
'left' becomes 'l' (common abbreviation).
'on' says to put letters next to each other.
'the day before' becomes 'eve' (I've seen this before).
'taking' is an insertion indicator.
'eve' enclosing 'a' is 'eave'.
'l'+'eave'='LEAVE'
(Other definitions for leave that I've seen before include "Brexit's aim" , "Don't take - time off" , "Quit; permission" , "Deposit" , "Go - on holidays?" .)