Surly Republican spreads nonsense (5)
I believe the answer is:
gruff
'surly' is the definition.
(I've seen this before)
'republican spreads nonsense' is the wordplay.
I cannot really understand how this works, but
'republican' could be 'r' (abbreviation in US politics) and 'r' is located in the answer.
'nonsense' could be 'guff' (I've seen this before) and 'guff' is located in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for gruff that I've seen before include "Abrupt in sound or manner" , "Curt and surly" , "Surly -- rough-spoken" , "Husky" , "Rasping - ungracious" .)