Pretender says, 'I'm after the Queen' (8)

I believe the answer is:

imposter

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'pretender' is the definition.
(I know that pretender can be written as imposter)

'i'm after the queen' is the wordplay.
'after' becomes 'post' (prefix meaning after, eg post-war).
'the queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'im'+'post'+'er'='IMPOSTER'

'says' acts as a link.
I am not very happy about this link. It may belong to another bit of the clue.

Can you help me to learn more?

(Other definitions for imposter that I've seen before include "One assuming a false identity" , "One who pretends to be another" , "One pretends to be someone else" , "One who makes deceitful pretences" , "Cheat" .)

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

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