Nine to perform and sing (6)
I believe the answer is:
intone
'sing' is the definition.
(I know that intone is a more specific form of the action sing)
'nine to perform' is the wordplay.
'perform' is an anagram indicator (I've seen 'performing' mean this).
'nine'+'to'='nineto'
'nineto' anagrammed gives 'INTONE'.
'and' is the link.
(Other definitions for intone that I've seen before include "Speak in chanting voice" , "Recite with little variation in pitch" , "Recite in a chanting voice" , "Recite without inflection" , "Speak in chant or drone" .)