Goose (6)
'goose' is the definition.
(male goose)
This is the entire clue.
(Other definitions for gander that I've seen before include "Male bird - look" , "He has webbed feet" , "waterbird" , "Male goose - quick look" , "Ranged over the bird" .)
(Another definition for simp that I've seen is " who is easily imposed upon?".)