You could do a pair of clowns, but the only anthias I would recommend for that size tank would be a fathead anthias. Other anthias like to school and do well in large groups, plus they get larger. The fathead isn't as active, stays smaller, and doesn't need to be kept in groups.
I would go with the 6-line, a pair of clowns, one more "swimming" fish, and a bottom dweller (my personal recommendation would be a goby/shrimp combo). I agree with avoiding the anthia, although I normally don't go with the concept of banning certain fish from certain sized tanks. It just seems to me that anthias really utilize all of the tank space and love having tons of room.
Thanks guys i ordered 2 clowns lastnight... will they be fine together if they are not a "paired" couple?
A pair of clownfish, even the least aggressive, once sexally mature, will dominate a nano. A sixline is a very aggressive fish, especially in a small tank.
Think about the natural habitat of anthias, riding the current over the reef, and you my reconsider the advisability of anthias in a nano.
If they have already sexually matured, you must have a male and female or two males. If you have two females, you will have one clown.