Design phase mishandled (5)

I believe the answer is:

shape

'design' is the definition.
(thesaurus)

'phase mishandled' is the wordplay.
'mishandled' indicates an anagram.
'phase' is an anagram of 'SHAPE'.

(Other definitions for shape that I've seen before include "Phase (anag.)" , "Good physical form" , "Form; mould" , "External form" , "Heaps (anag.)" .)

I've seen this clue in The Sun.

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