Advanced knacks are knacks that combine the skill in several other knacks to create something larger that it's parts. To qualify for advanced knacks within a skill a person mush have at least six (6) ranks in the skill's basic knacks and at least three (3) in one of them.
For example a Perfumer needs to be trained in inter-personal skill (ex. flattery), alchemy and fashion. Someone skilled in fashion may know what fragrances are in fashion at the moment but cannot create nor sell it. Similarly the alchemist may create the fragrances but may not know what are in fashion at the moment and the trends.