Drew pair of spectacles on bird — a crow (4-1-6-3)

I believe the answer is:
cock-a-doodle-doo
'a crow' is the definition.
(thesaurus)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for cock-a-doodle-doo that I've seen before include "Early morning farmyard cry" , "Farmyard crow" .)
I've seen this clue in The Times.
Want a hint initially instead of a full solution?
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