We break egg — wake up (5)
I believe the answer is:
rouse
'wake up' is the definition.
(I've seen this before)
'we break egg' is the wordplay.
'we' becomes 'us'.
'break' indicates putting letters inside.
'egg' becomes 'roe' (roe is a kind of egg).
'us' inserted into 'roe' is 'ROUSE'.
(Other definitions for rouse that I've seen before include "Cause to wake up and come alert" , "Cause to become awake" , "Get going" , "Move" , "cause to wake or to become active" .)