Look grand with leading lady (6)
I believe the answer is:
gander
'look' is the definition.
(informal term for a look or glance)
'grand with leading lady' is the wordplay.
'grand' becomes 'g' (G is short for grand as in a thousand).
'with' becomes 'and'.
'leading lady' becomes 'ER' (Elizabeth Regina).
'g'+'and'+'er'='GANDER'
(Other definitions for gander that I've seen before include "Ranged over the bird" , "Male 7 across" , "Butchers - goose" , "A butcher's -- bird" , "Ranged about with male goose" .)