Free additional note with one hundred invested (9)
I believe the answer is:
extricate
'free' is the definition.
(extricating is a kind of freeing)
'additional note with one hundred invested' is the wordplay.
'additional' becomes 'extra' (extra means additional or surplus).
'note with' becomes 'te' (musical note. I am not sure about the 'with' bit.).
'one' becomes 'i' (Roman numeral).
'hundred' becomes 'c' (Roman numeral).
'invested' is an insertion indicator.
'i'+'c'='ic'
'extra'+'te'='extrate'
'extrate' placed around 'ic' is 'EXTRICATE'.
Can you help me to learn more?
(Other definitions for extricate that I've seen before include "wriggle free" , "Free (someone) from difficulty" , "Disentangle, set free" , "Get free from" , "Free from complicated situation" .)