Unruly lads can cause this (7)
I believe the answer is:
scandal
'cause this' is the definition.
The definition suggests a singular noun which matches the answer.
'unruly lads can' is the wordplay.
'unruly' indicates an anagram.
'lads'+'can'='ladscan'
'ladscan' is an anagram of 'SCANDAL'.
Can you help me to learn more?
(Other definitions for scandal that I've seen before include "Public disgrace" , "something injurious to one's reputation" , "Outraging event" , "Subject of Sheridan's school" , "Malicious gossip" .)