I call for a change of colour (5)
I believe the answer is:
lilac
'colour' is the definition.
(lilac is a shade of purple)
'i call for a change' is the wordplay.
'for a change' indicates an anagram.
'i'+'call'='icall'
'icall' is an anagram of 'LILAC'.
'of' acts as a link.
(Other definitions for lilac that I've seen before include "Pale purple - flowering tree" , "Plant" , "Pale mauve colour for a flower" , "Fragrant shrub; colour" , "Pinkish purple - shrub" .)