Avoid parties with favourite from the south (8)
I believe the answer is:
sidestep
'avoid' is the definition.
(I know that sidestep is a more specific form of the action avoid)
'parties with favourite from the south' is the wordplay.
'parties' becomes 'sides' (eg the two parties in an argument).
'with' says to put letters next to each other.
'favourite' becomes 'pet' (synonyms).
'from the south' says the letters should be written backwards (in a down clue, letters go up).
'pet' back-to-front is 'tep'.
'sides'+'tep'='SIDESTEP'
(Other definitions for sidestep that I've seen before include "Find a way round" , "Shift to right or left" , "To avoid" , "Dodge (an issue?)" , "Dodge - circumvent" .)