Flock of geese (6)
I believe the answer is:
gaggle
'flock of geese' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for gaggle that I've seen before include "Group of geese" , "Alternative name for a flock of geese" , "flock of birds" , "Disorderly group" , "Flock of geese on the ground" .)