Extremely dull criminal I arrested (9)

I believe the answer is:

dreariest

'extremely dull' is the definition.

'criminal i arrested' is the wordplay.
'criminal' indicates anagramming the letters.
'i'+'arrested'='iarrested'
'iarrested' is an anagram of 'DREARIEST'.

(Other definitions for dreariest that I've seen before include "Most tiresome" , "Not the most exciting" .)

I've seen this clue in The Times.

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