Birds in a gaggle (5)
I believe the answer is:
geese
'birds in a gaggle' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for geese that I've seen before include "Stupid people" , "Birds; silly people" , "Grey-lags" , "Water birds; fools" , "Edible water birds" .)