A dangerous thing to get stroppy with! (5)
I believe the answer is:
razor
'a dangerous thing' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe you can see an association between them that I can't see?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for razor that I've seen before include "Tonsorial tool" , "Stubble cutter" , "Shaver" , "Device for shaving" , "Shaver's kit" .)