Bad behaviour did seem wrong (7)
I believe the answer is:
misdeed
'bad behaviour' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'did seem wrong' is the wordplay.
'wrong' indicates an anagram.
'did'+'seem'='didseem'
'didseem' is an anagram of 'MISDEED'.
Can you help me to learn more?
(Other definitions for misdeed that I've seen before include "crime" , "Illegal/wicked act" , "Wicked/illegal act" , "Improper act" , "Wicked or illegal act" .)