Bird seen by wharf in London (6)
I believe the answer is:
canary
'bird' is the definition.
(canary is a kind of bird)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for canary that I've seen before include "Bird from an island group" , "Finch prized for its song" , "This flies" , "Yellow bird, formerly taken down mines" , "a sort of finch" .)