Girl leading procession millions resolved to jeer at (9)
I believe the answer is:
majorette
'girl leading procession' is the definition.
I can't judge whether this definition defines the answer.
'millions resolved to jeer at' is the wordplay.
'millions' becomes 'm' (abbreviation).
'resolved' indicates anagramming the letters.
'to'+'jeer'+'at'='tojeerat'
'tojeerat' anagrammed gives 'ajorette'.
'm'+'ajorette'='MAJORETTE'
Can you help me to learn more?
(Other definitions for majorette that I've seen before include "Girl in parade wearing military style costume" , "Marching band leader" , "Female baton twirler" , "Baton-twirling marcher" .)