May look ducky, but it's dangerous! (5)
I believe the answer is:
decoy
'may' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for decoy that I've seen before include "'Lure, bait (5)'" , "Imitation creature used to attract others" , "Thing used to lure animal into trap" , "Entrap" , "Red herring" .)