Well-behaved time before, honestly (5)
I believe the answer is:
truly
'honestly' is the definition.
(I've seen this in another clue)
'well-behaved time before' is the wordplay.
'well-behaved' becomes 'ruly' (I've seen this before).
'time' becomes 't' (abbreviation).
'before' says to put letters next to each other.
'ruly' put after 't' is 'TRULY'.
(Other definitions for truly that I've seen before include "Indeed" , "Verily" , "Really, genuinely" , "Genuinely, properly" , "with accuracy" .)