In colour, it can be described as great (5)
I believe the answer is:
titan
'great' is the definition.
(I've seen this before)
'in colour it' is the wordplay.
'in' means one lot of letters goes inside another.
'colour' becomes 'tan' (tan is a kind of colour).
'tan' placed around 'it' is 'TITAN'.
'can be described as' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for titan that I've seen before include "Goddess" , "Taint (anag.)" , "An old Greek god - Atlas was one" , "Hyperion, for example" , "Taint in old Greek god" .)