Crossword Genius

What sweetheart shows heart? (4)

Ross

I believe the answer is:

core

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'heart?' is the definition.
('core' can be a synonym of 'heart')

'what sweetheart' is the wordplay.
'what' becomes 'cor' (I can't explain this - if you can you should give a lot more credence to this answer).
'sweetheart' becomes 'e' (the heart/centre of 'sweet').
'cor'+'e'='CORE'

'shows' is the link.

Can you help me to learn more?

(Other definitions for core that I've seen before include "The centre of an object" , "Nucleus" , "Drilled rock sample" , "The centre part, as of an apple" , "Kernel" .)

I've seen this clue in The Telegraph.
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