Rude part, figuratively speaking (6,8)
I believe the answer is:
vulgar fraction
'figuratively speaking' is the definition.
The definition suggests a singular noun which matches the answer.
'rude part' is the wordplay.
'rude' becomes 'vulgar' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'part' becomes 'fraction' (fraction is a kind of part).
'vulgar'+'fraction'='VULGAR FRACTION'
Can you help me to learn more?
(Other definitions for vulgar fraction that I've seen before include "Mathematical expression" , "in which division is evident" , "in bar between five and six, for example" .)