Violet almost changed colour (5)
I believe the answer is:
'colour' is the definition.
(I know that olive is a type of chromatic color)
'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 off 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" .)