The term 'in a lather (with 'UP')' is composed of three crossword solutions: HET (3 letters), WORKED (6 letters), and SOAPED (6 letters). HET is an informal verb meaning to heat something UP, WORKED is a verb meaning to do labor or effort, and SOAPED is a verb meaning to wash with soap. Therefore, the phrase 'in a lather (with 'UP')' can be interpreted as being heated UP while doing labor or effort, and washing with soap.