Acorns ain't nuts, they're flowers (10)
I believe the answer is:
carnations
'flowers' is the definition.
(carnation is a kind of flower)
'acorns ain't nuts' is the wordplay.
'nuts' is an anagram indicator (nuts can mean crazy).
'acorns'+'aint'='acornsaint'
'acornsaint' is an anagram of 'CARNATIONS'.
'they're' acts as a link.
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