Final answer:
Wolfgang Amadeus Mozart effectively worked within the patronage system, where he composed for an aristocratic audience before the rise of the public concert.
Step-by-step explanation:
The composer who worked well under the patronage system was Wolfgang Amadeus Mozart. Mozart composed for the aristocracy, meaning his primary audience was small, upper-class, and well-versed in music. This system was a prevalent means of support for artists before the emergence of the middle class and the large public concerts that characterized the Romantic period. The patronage system allowed composers like Mozart to create music under the financial support of the nobility.