Nine's a trick short of a full deck (6)

I believe the answer is:

insane

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'short of a full deck' is the definition.
Both the answer and definition are adjectives. Maybe there's a link between them I don't understand?

'nine's a trick' is the wordplay.
'trick' indicates an anagram (a tricky version of the letters).
'nines'+'a'='ninesa'
'ninesa' is an anagram of 'INSANE'.

Can you help me to learn more?

(Other definitions for insane that I've seen before include "Irresponsible" , "Out of one's mind" , "Sienna (anag.)" , "Quite mad" , "Wild < cuckoo < cracked" .)

I've seen this clue in the Sydney Morning Herald.

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