It's wrong to hiss at our continental friends (5)
I believe the answer is:
amiss
'it's wrong' is the definition.
(synonyms)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for amiss that I've seen before include "astray" , "Mistaken" , "inappropriately" , "Wrongly" , "In an inappropriate way" .)