The exacting part of 'Richard III' (4)

I believe the answer is:

hard

'the exacting' is the definition.
(I've seen this in another clue)

'part of richard iii' is the wordplay.
'part of' indicates a hidden word.
'HARD' is hidden within 'richard iii'.

(Other definitions for hard that I've seen before include "impenetrable" , "Solid, firm, rigid" , "Difficult - firm" , "Newspaper's sure" , "Difficult; severe" .)

I've seen this clue in the Evening Standard.

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