Tonsil treater, in brief Crossword Clue

 The answer to the crossword clue "Tonsil treater, in brief" is ENT.

ENT stands for ear, nose, and throat. Otolaryngologists, or ENT doctors, specialize in diagnosing and treating conditions of the ears, nose, throat, and head and neck. They also treat tonsillitis, which is an infection of the tonsils.

Here are some other clues that could be used for this answer:

Doctor who treats tonsillitis

Ear, nose, and throat specialist

Head and neck surgeon

I hope this helps!