struka

1. profession; trade
   Po struci je građevinski inženjer. — He is a civil engineer by profession.
   Posle fakulteta nije mogla da nađe posao u struci. — After university she couldn't find a job in her field.
2. field; discipline; branch
   To pitanje nije iz moje struke. — That question isn't from my field.
3. the experts; the profession
   Struka je protiv ovakve reforme zdravstva. — The experts are against this kind of health reform.

Common phrases: po struci "by profession" and raditi u struci "to work in one's field".