Quick, before the sun gets to! (6)
I believe the answer is:
presto
'quick' is the definition.
(I've seen this before)
'before the sun gets to' is the wordplay.
'before' becomes 'pre' (prefix meaning 'before').
'the sun' becomes 'S' (abbreviation).
'gets' says to put letters next to each other.
'pre'+'s'+'to'='PRESTO'
(Other definitions for presto that I've seen before include "rapidly" , "(Musically) fast" , "In a quick tempo (music)" , "Hey . . . . ., says the magician (6)" , "Hey, it's a magician's word" .)