Foals are frisky after a tonic perhaps (3-2)
I believe the answer is:
sol-fa
'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" .)