A small botanical publication? (7)

I believe the answer is:

leaflet

I'm a little stuck... Click here to teach me more about this clue!

'publication?' is the definition.
(I know that leaflet is a type of book)

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for leaflet that I've seen before include "Printed handout" , "small part of plant" , "Single printed sheet" , "Advertising sheet" , "Flier" .)

I've seen this clue in the Evening Standard.

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