Unaware, having left one in plain wrapping (9)

I believe the answer is:

oblivious

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'unaware' is the definition.
(similar in meaning)

'left one in plain wrapping' is the wordplay.
'left' becomes 'l' (common abbreviation).
'one' becomes 'I' (Roman numeral).
'in plain' becomes 'obvious' (similar in meaning. I am not sure about the 'in' bit.).
'wrapping' means one lot of letters goes inside another.
'l'+'i'='li'
'li' placed into 'obvious' is 'OBLIVIOUS'.

'having' acts as a link.

Can you help me to learn more?

(Other definitions for oblivious that I've seen before include "Blind (to)" , "Absent-mindedly unaware" , "Not noticing" , "Unconscious" , "Totally unaware" .)

I've seen this clue in The Daily Express.

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