Loud bird-call audible in poem (5)

I believe the answer is:

haiku

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'poem' is the definition.
(I know that haiku is a type of poem)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for haiku that I've seen before include "Stylised Japanese poem of 17 syllables" , "Eastern poetry" , "Japanese poem of seventeen syllables comprising three lines" , "Short Japanese poem" , "Seventeen-syllable Japanese poem" .)

I've seen this clue in The Times.

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