A name meaning very little (4)
I believe the answer is:
atom
'little' is the definition.
(thesaurus)
'a name meaning very' is the wordplay.
'name meaning very' becomes 'tom' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a'+'tom'='ATOM'
Can you help me to learn more?
(Other definitions for atom that I've seen before include "Basic unit of a chemical element" , "The tiniest particle" , "A really tiny piece of something" , "Minute particle" , "Something very small perhaps" .)