### Clue: Serbians detest commerce? At heart, I don't care (4,2)
### Answer: BITE ME 
 ### Explanation: Definition: I don't care
Inner letters ('at heart') of 'ser**BI**ans de**TE**st com**ME**rce'.. Not an expression that I have come across before (at least with this meaning), but a little trawling comes up with it in .