Crossword Genius

Unseen, one observing another corrupt occultist in healer (7-8)

Ross

I believe the answer is:

curtain-twitcher

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'unseen one observing another' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'corrupt occultist in healer' is the wordplay.
'corrupt' becomes 'taint' (synonyms).
'occultist' becomes 'witch' (witch is a kind of occultist).
'in' means one lot of letters goes inside another.
'healer' becomes 'curer' (I've seen this before).
'taint'+'witch'='taintwitch'
'taintwitch' going inside 'curer' is 'CURTAIN-TWITCHER'.

Can you help me to learn more?

I've seen this clue in The Telegraph.
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