Insect embodies one good colour (5)
I believe the answer is:
beige
'colour' is the definition.
(beige is a kind of colour)
'insect embodies one good' is the wordplay.
'insect' becomes 'bee' (bee is a type of insect).
'embodies' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'good' becomes 'g' (abbreviation).
'i'+'g'='ig'
'bee' enclosing 'ig' is 'BEIGE'.
(Other definitions for beige that I've seen before include "Pale brown" , "Light sandy fawn colour" , "Fawn or buff" , "Light brown" , "Fawn-coloured" .)