Nudist regularly seen in the French promontory in painting (9)
I believe the answer is:
landscape
'painting' is the definition.
(I know that landscape is a type of painting)
'nudist regularly seen in the french promontory' is the wordplay.
'regularly seen' indicates alternate letters.
'in' means one lot of letters goes inside another.
'the french' becomes 'la' ('the' in French).
'promontory' becomes 'cape' (both can mean a headland).
The alternating letters of 'nudist' are 'nds'.
'la'+'cape'='lacape'
'nds' inserted inside 'lacape' is 'LANDSCAPE'.
'in' is the link.
(Other definitions for landscape that I've seen before include "scene" , "Views" , "Outdoor painting" , "Expanse of scenery" , "Scenic picture" .)