Crossword Puzzle Centers of intellectual activity

Clue: Centers of intellectual activity

Centers of activity (e.g. FOCI with 4 letters)
Post office activity, or a hint to this puzzle's theme (LETTERSORTING with 13 letters)
Office activity (FAXING with 6 letters)
Protest activity for ANWR drilling proponents against EPA officials? (SNOWBALLING with 11 letters)
Centers of great activity (LOCI with 4 letters)
Intellectual show-offs (PEDANTS with 7 letters)
Activity centers (e.g. HOTBEDS with 7 letters)
Witty activity (CRACKINGAJOKE with 13 letters)
Cookbook offering (RECIPE with 6 letters)
Military operations centers (BASES with 5 letters)