Genuine article secured by relative, almost 100 (9)
I believe the answer is:
authentic
'genuine' is the definition.
(similar in meaning)
'article secured by relative almost 100' is the wordplay.
'article' becomes 'the' (the definite article in English).
'secured by' is an insertion indicator (I've seen this in other clues).
'relative' becomes 'aunt' (aunt is a kind of relative).
'almost i00' becomes 'ic' (I can't explain this - if you can you should give a lot more credence to this answer).
'the' inserted within 'aunt' is 'authent'.
'authent'+'ic'='AUTHENTIC'
Can you help me to learn more?
(Other definitions for authentic that I've seen before include "24 [LEGIT]" , "Bona fide" , "Genuine, not a copy" , "reliable" , "Real, genuine" .)