Bream changed colour (5)
I believe the answer is:
amber
'colour' is the definition.
(amber is a kind of colour)
'bream changed' is the wordplay.
'changed' is an anagram indicator.
'bream' is an anagram of 'AMBER'.
(Other definitions for amber that I've seen before include "Colour of warning" , "Ornamental fossil resin" , "Yellow, translucent fossil resin" , "Yellowish fossilised resin" , "Yellow-brown colour as of bream" .)