Not suitable for making paint (5)
I believe the answer is:
inapt
'not suitable' is the definition.
(I've seen this before)
'making paint' is the wordplay.
'making' indicates an anagram.
'paint' with letters rearranged gives 'INAPT'.
'for' is the link.
(Other definitions for inapt that I've seen before include "Not fit, unsuitable" , "badly judged" , "Not suitable or appropriate" , "Free from deceit" , "It's clumsy" .)