Fight dirty (4)
I believe the answer is:
blue
This might be a double definition.
'fight' is the first definition.
The answer and definition can be both human attributes as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'dirty' is the second definition.
(blue can mean pornographic)
Can you help me to learn more?
(Other definitions for blue that I've seen before include "Spend all at once - colour" , "gloomy" , "Colour - smutty" , "Terrible commotion?" , "Oxbridge sports award" .)