Van Gogh painting is about to go up (6)
I believe the answer is:
irises
'van gogh painting' is the definition.
'is about to go up' is the wordplay.
'about' is an insertion indicator.
'to go up' becomes 'rise' (rising is a kind of going up**).
'is' going around 'rise' is 'IRISES'.
(Other definitions for irises that I've seen before include "Subject for van Gogh" , "Flowers found in the eye" , "Flowers and parts of eyes" , "blooms" , "Eye membranes or showy flowers." .)