Violet almost changed colour (5)
I believe the answer is:
olive
'colour' is the definition.
(olive is a kind of colour)
'violet almost changed' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'changed' is an anagram indicator.
'violet' with its final letter taken away is 'viole'.
'viole' is an anagram of 'OLIVE'.
(Other definitions for olive that I've seen before include "Small green tree-fruit, nice in martini" , "One [TYPE OF TREE] is from the Mediterranean" , "Oily stone fruit" , "Girl's name - colour" , "I love this fruit" .)