Vocally in top form? (2,4)
I believe the answer is:
on song
'vocally' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for on song that I've seen before include "in fine form" , "Performing well (informal)" , "on top form?" , "Vocally" , "In superlative form" .)