Bird saved by scoter, geese knocked over (5)
I believe the answer is:
egret
'bird' is the definition.
(egret is a kind of bird)
'scoter geese knocked over' is the wordplay.
'over' indicates the answer is hidden within the clue (the clue contains or goes 'over' the answer).
'knocked' is a reversal indicator (I've seen 'knocking' mean this).
'terge' can be found hidden inside 'scoter geese'.
'terge' backwards is 'EGRET'.
'saved by' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for egret that I've seen before include "one with plume" , "Stork-like bird" , "Heron-like wader" , "Kind of heron with long white feathers" , "One of a pair of waders" .)