Noble type of king lacking protection (4)
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I believe the answer is:
earl
'noble' is the definition.
(earl is a kind of noble)
'type of king lacking protection' is the wordplay.
I cannot quite see how this works, but
'king' could be 'r' (abbreviation for rex, king in Latin) and 'r' is located in the answer.
The remaining letters 'eal' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for earl that I've seen before include "Sandwich perhaps" , "Lear (anag)" , "Husband of a countess" , "Countesss husband" , "One who's been elevated" .)
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