Brigand, ergo, has a look (6)
I believe the answer is:
gander
'a look' is the definition.
(informal term for a look or glance)
'brigand ergo has' is the wordplay.
'has' indicates the answer is hidden within the clue.
'GANDER' is hidden within 'brigand ergo'.
(Other definitions for gander that I've seen before include "waterbird" , "'What's sauce for the goose is sauce for the . . . . . .'" , "town in Newfoundland" , "Ranged about with male goose" , "A butcher's -- bird" .)