Colour of bream at sea (5)
I believe the answer is:
Here is my best explanation:
'colour' is the definition.
(amber is a kind of colour)
'bream at sea' is the subsidiary indication.
'at sea' is an anagram indicator.
'bream' anagrammed gives 'amber'.
'of' is the link.
(Other definitions for amber that I've seen before include "Light colour between red and green", "Warning colour", "Prepare-to-stop signal", "Fossil resin - bream (anag)", "Fossil resin used in jewellery", "Yellow-brown colour as of bream", "Deep yellow", "Traffic light colour", "Fossilised resin used in jewellery" and "Young bird of prey".)