Earlier than (6)
![Ross](/clue/static/ross-mug.min.png)
'earlier than' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for before that I've seen before include "In front of or previous to" , "Defy, withstand" , "During the period preceding" , "In front of (something)" , "In advance" .)