Disorderly suitor sadly admits nothing (7)
I believe the answer is:
riotous
'disorderly' is the definition.
('riotous' can be a synonym of 'disorderly')
'suitor sadly admits nothing' is the wordplay.
'sadly' indicates an anagram.
'admits' is an insertion indicator.
'nothing' becomes 'o' (looks like zero - 0).
'suitor' with letters rearranged gives 'riotus'.
'riotus' enclosing 'o' is 'RIOTOUS'.
(Other definitions for riotous that I've seen before include "Behaving wildly" , "Of mob, disorderly and unruly" , "Anarchic" , "Boisterous and unrestrained" , "wild and unruly" .)