Nun is ace criminal in drag (8)
I believe the answer is:
nuisance
'drag' is the definition.
(thesaurus)
'nun is ace criminal' is the wordplay.
'criminal' indicates anagramming the letters.
'nun'+'is'+'ace'='nunisace'
'nunisace' with letters rearranged gives 'NUISANCE'.
'in' is the link.
(Other definitions for nuisance that I've seen before include "Source of annoyance or aggravation" , "It causes inconvenience or annoyance" , "Bothersome pest" , "Something which annoys" , "'Pest, annoyance (8)'" .)