Range of colours sure to include trace of light blue (7)
I believe the answer is:
yellows
'range of colours' is the definition.
'yellows' can be an answer for 'colours' (yellow is a kind of colour). I am not sure about the 'range of' bit.
'sure to include trace of light blue' is the wordplay.
'sure' becomes 'yes' (both are affirmative answers).
'to include' indicates putting letters inside.
'trace of' says to take the initial letters.
'blue' becomes 'low' (I've seen this in another clue).
The first letter of 'light' is 'l'.
'l'+'low'='llow'
'yes' placed around 'llow' is 'YELLOWS'.
Can you help me to learn more?
(Other definitions for yellows that I've seen before include "Turns lurid, perhaps" , "shows age" , "Primary colours" , "Plant disease" , "shades of autumn?" .)