Thorough knowledge can be seen (7)

I believe the answer is:

insight

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'thorough knowledge' is the definition.
'insight' can be an answer for 'knowledge' (insight is a kind of knowledge). I am not certain of the 'thorough' bit.

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for insight that I've seen before include "Deep understanding" , "Imaginative penetration" , "percipience" , "famous Sunday Times team" , "Awareness" .)

I've seen this clue in The Irish News.

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