Socialist turned up by county town (5)
I believe the answer is:
derby
'county town' is the definition.
'derby' can be an answer for 'town'. I'm not sure about the 'county' bit.
'socialist turned up by' is the wordplay.
'socialist' becomes 'red' (socialism is often associated with the colour red).
'turned up' says the letters should be written in reverse.
'red' written backwards gives 'der'.
'der'+'by'='DERBY'
Can you help me to learn more?
(Other definitions for derby that I've seen before include "American bowler" , "confrontation between neighbours" , "Annual race at Epsom" , "Epsom horse-race" , "20 horse 12" .)