Happy at home about nothing? There's argument (10)
I believe the answer is:
contention
'argument' is the definition.
(I know that argument can be written as contention)
'happy at home about nothing?' is the wordplay.
'happy' becomes 'content' (associated in meaning).
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'about' is an insertion indicator.
'nothing?' becomes 'O' (looks like zero - 0).
'in' going around 'o' is 'ion'.
'content'+'ion'='CONTENTION'
'there's' acts as a link.
(Other definitions for contention that I've seen before include "Judgment" , "heated argument" .)