Chopped up hake when gutted (4)

I believe the answer is:

hewn

I'm a little stuck... Click here to teach me more about this clue!

'chopped' is the definition.
(I've seen this before)

'up hake when gutted' is the wordplay.
'when' anagrams to 'HEWN'.
Though, I'm unsure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for hewn that I've seen before include "Hacked" , "Cut - carved - chopped" , "Cut with blows" , "Chopped roughly" , "Felled" .)

I've seen this clue in The Guardian.

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