Discover, when you come upon unconscious (4,3)

I believe the answer is:

find out

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'discover' is the definition.
(I know that discover is a more specific form of the action discover)

'come upon unconscious' is the wordplay.
'come upon' becomes 'find' (synonyms).
'unconscious' becomes 'out' (similar in meaning).
'find'+'out'='FIND OUT'

'when you' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.

Can you help me to learn more?

(Other definitions for find out that I've seen before include "Ascertain" , "one has made a call pointlessly" , "'Discover (4,3)'" .)

I've seen this clue in the Evening Standard.

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