Unwise Trump-Biden clash spilling first blood (9)
I believe the answer is:
imprudent
'unwise' is the definition.
(similar in meaning)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for imprudent that I've seen before include "not wise" , "Without forethought" , "Rash, lacking discretion" , "Lacking in good sense or caution" , "'making the wrong choices'?" .)