Before the expected time (5)
'before the expected time' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for early that I've seen before include "Untimely" , "Forward" , "in the morning?" , "Premature" , "Infancy, when Wordsworth had 5 across of 5 down" .)
(Other definitions for earlier that I've seen before include "at a previous date" , "of a bygone age?" , "(Happening) before in time" , "Formerly" , "Further back in time" .)