First to prepare for painting (5)
I believe the answer is:
prime
This clue is a double definition.
'first' is the first definition.
(similar in meaning)
'prepare for painting' is the second definition.
(I've seen this in another clue)
'to' is the link.
(Other definitions for prime that I've seen before include "Chief or most important, like a minister" , "Of first quality" , "Chief or best quality" , "Two or three, for example" , "Best - get ready" .)