Amateurish, inactive, retains 50% hope (8)

I believe the answer is:

inexpert

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But I can't explain it at all! Could you help me understand?

(Other definitions for inexpert that I've seen before include "with little skill" , "not clever" , "unprofessional" , "Inept rex may be lacking in skill" , "Lacking know-how" .)

I've seen this clue in The Hindu.

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