Wild boar turned quieter in garden (9)
I believe the answer is:
arboretum
'garden' is the definition.
(I've seen this before)
'wild boar turned quieter' is the wordplay.
I cannot really understand how this works, but
an anagram of 'boar' is 'arbo' which is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'in' is the link.
Can you help me to learn more?
(Other definitions for arboretum that I've seen before include "Place for cultivation of 19s" , "Botanical tree garden" , "there's high growth" , "Place for cultivation of trees" , "Botanic garden of trees" .)