Costume of monk initially upsetting a large regular (8)

I believe the answer is:

habitual

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'regular' is the definition.
(synonyms)

'costume of monk initially upsetting a large' is the wordplay.
'costume of monk' becomes 'habit' (I am not sure about this - if you are sure you should believe this answer much more).
'initially' says to take the initial letters.
'large' becomes 'L' (eg in clothes sizes).
The initial letter of 'upsetting' is 'u'.
'habit'+'u'+'a'+'l'='HABITUAL'

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(Other definitions for habitual that I've seen before include "Commonly practised" , "set" , "Traditional" , "A halibut? (anag)" , "Chronic" .)

I've seen this clue in The Daily Express.

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