Oscar Peterson ultimately dotes on swinging solo (2,4,3)
I believe the answer is:
on ones tod
'solo' is the definition.
(I've seen this before)
'oscar peterson ultimately dotes on swinging' is the wordplay.
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'ultimately' says to take the final letters.
'swinging' indicates anagramming the letters.
The last letter of 'peterson' is 'n'.
'dotes'+'on'='doteson'
'doteson' anagrammed gives 'onestod'.
'o'+'n'+'onestod'='ON ONES TOD'
(Other definitions for on ones tod that I've seen before include "Alone" , "solo" , "reverse of 9 [AIDED] ?" .)