Is clindamycin safe and effective to take for tonsillitis?

Possibly but: Clindamycin is effective but has a black box warning. It can occasionally cause a severe colitis due to a bacteria called C. difficile. Other antibiotics can cause this also, but more likely with clindamycin. Penicillin or amoxicillin would be the first choice, unless your allergic to penicillin. If allergic, clindamycin is a reasonable choice or azithromycin(less likely to cause colitis).