When upset Eddy changed colour (4)
I believe the answer is:
dyed
'changed colour' is the definition.
(I've seen this before)
'when upset eddy' is the wordplay.
'when upset' indicates an anagram.
'eddy' with letters rearranged gives 'DYED'.
(Other definitions for dyed that I've seen before include "(Of fabric) coloured" , "Stained with a new colour" , "Artificially coloured" , "Coloured by dipping in liquid" , "A shade unnatural" .)