Foals are frisky after a tonic perhaps (3-2)

I believe the answer is:

sol-fa

I'm a little stuck... Click here to teach me more about this clue!

'a tonic perhaps' is the definition.
I can't judge whether this defines the answer.

'foals are frisky' is the wordplay.
'are frisky' indicates an anagram.
'foals' with letters rearranged gives 'SOL-FA'.

'after' acts as a link.

Can you help me to learn more?

(Other definitions for sol-fa that I've seen before include "Singing system using syllables" , "System for teaching singing" , "Method of teaching music" , "System for naming notes of a scale" , "System of note naming" .)

I've seen this clue in The Globe and Mail.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.