The crossword solution for the term 'ACTOR's Assistant' is 'DRESSER', which is a seven letter word. A DRESSER is a person who assists an ACTOR with their costume and makeup before a performance. They are responsible for helping the ACTOR get into costume, ensuring that the costume fits properly, and helping the ACTOR with any makeup or hair styling needs. The DRESSER also helps the ACTOR with any quick changes that may be needed during a performance.