Crossword Genius

Feeble dope, holding three high cards, extremely naive (4-5)

Ross

I believe the answer is:

weak-kneed

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'feeble' is the definition.
(thesaurus)

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(Other definitions for weak-kneed that I've seen before include "Lacking moral courage in legs?" , "Feeble" .)

I've seen this clue in The Telegraph.
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