Doing it up' is a phrase that means to do something in an extravagant or impressive way. It can be used to describe a person who is dressing up for a special occasion, or a room that has been decorated with expensive furniture and decorations. The crossword solution for 'doing it up' is 'LACING', which is the act of tying a string, ribbon, or other material through two or more holes in order to fasten something together. LACING is often used to secure shoes, corsets, and other garments.