Be at the front earlier (6)
I believe the answer is:
before
'earlier' is the definition.
(synonyms)
'be at the front' is the wordplay.
'at' is a charade indicator (letters next to each other).
'the front' becomes 'fore' (fore is a kind of front).
'be'+'fore'='BEFORE'
(Other definitions for before that I've seen before include "Earlier in time" , "Previously ? in front" , "On a previous occasion" , "In front - earlier" , "In front of or previous to" .)