It won't hold much soap, note, if shaken (8)
I believe the answer is:
teaspoon
'it won't hold much' is the definition.
The definition suggests a singular noun which matches the answer.
'soap note if shaken' is the wordplay.
'soap note' anagrams to 'TEASPOON'.
But, I am not sure how this is indicated.
Can you help me to learn more?
(Other definitions for teaspoon that I've seen before include "5 ml container" , "Small medicine dispensing unit" , "Small stirrer" , "Five millilitres (cookery)" , "It creates a stir" .)