Set off from location south of service area (12)
I believe the answer is:
counterpoint
'set off' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'location south of service area' is the wordplay.
I cannot quite understand how this works, but
'location' could be 'point' (point is a kind of location) and 'point' is found within the answer.
'of' could be 'o' and 'o' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'from' is the link.
Can you help me to learn more?
(Other definitions for counterpoint that I've seen before include "Foil" , "Combination of melodies" , "Melody added to another" , "Interplay of melodies" , "Compensate for" .)