Long time before noon (5)
I believe the answer is:
yearn
'long' is the definition.
(I know that long can be written as yearn)
'time before noon' is the wordplay.
'time' becomes 'year' (I've seen this in other clues).
'before' says to put letters next to each other.
'noon' becomes 'n'.
'year'+'n'='YEARN'
(Other definitions for yearn that I've seen before include "Desire, want" , "Pant - pine" , "Long - pine" , "Desire strongly" , "Curdle" .)