About article on smooth vegetable - on reflection it's well-balanced (2,2,4,4)
I believe the answer is:
on an even keel
'well-balanced' is the definition.
(I've seen this in another clue)
'about article on smooth vegetable on reflection' is the wordplay.
'about' means one lot of letters goes inside another.
'article' becomes 'an' (English indefinite article).
'smooth' becomes 'even' (similar in meaning).
'vegetable' becomes 'leek' (leek is a kind of vegetable).
'on reflection' says the letters should be written in reverse.
'leek' in reverse letter order is 'keel'.
'on'+'even'='oneven'
'an' going inside 'oneven' is 'onaneven'.
'onaneven'+'keel'='ON AN EVEN KEEL'
'it's' acts as a link.
(Other definitions for on an even keel that I've seen before include "In a stable condition" , "(Going) calmly" , "Running smoothly" , "Steady" , "Well-balanced" .)