Not much of an article to smile about (5)
I believe the answer is:
grain
'not much' is the definition.
The answer and definition can be both quantities as well as being singular nouns.
Maybe there's an association between them I don't understand?
'an article to smile about' is the wordplay.
'an article' becomes 'a' (the indefinite article in English).
'to smile' becomes 'grin' (synonyms).
'about' means one lot of letters goes inside another.
'a' inserted within 'grin' is 'GRAIN'.
'of' is the link.
Can you help me to learn more?
(Other definitions for grain that I've seen before include "Small hard seed of corn etc" , "Small particle - wood texture" , "Pattern of lines in wood" , "Small particle - weight" , "Small weight; seed" .)