The term SPIFF (UP) is an acronym for Sales Promotion Incentive Fund, which is a type of bonus given to salespeople to reward them for their performance. The crossword solutions for this term are NEATEN (6 letters), REDO (4 letters), POLISH (6 letters), GUSSY (5 letters), SPRUCE (6 letters), and SMARTEN (7 letters). All of these words refer to the idea of making something look better or more attractive, which is what a SPIFF does for a salesperson's performance.