Preserve most of huge painting (6)
I believe the answer is:
canvas
'painting' is the definition.
(canvas is a kind of painting)
'preserve most of huge' is the wordplay.
'preserve' becomes 'can' (canning is a kind of preserving).
'most of' means to remove the last letter.
'huge' becomes 'vast' (I've seen this before).
'vast' with its last letter removed is 'vas'.
'can'+'vas'='CANVAS'
(Other definitions for canvas that I've seen before include "Painting base" , "Intent, say" , "Tent material" , "Material often used by artist to paint on" , "Sailcloth" .)