1. Develop
   "we worked up an as of an appetite";
   - get up
    
2. Form or accumulate steadily
   "The storm worked up into a fierce hurricane";
   - build up, build
    
3. Bolster or strengthen
   "We worked up courage";
   - build up, build, ramp up
    
4. Come up with
   "We worked up an ad for our client";
   - work out

Derived forms: works up, working up, worked up

Type of: acquire, develop, get, grow, increase, produce