New game and books, a dark colour (7)
I believe the answer is:
magenta
'dark colour' is the definition.
'magenta' can be an answer for 'colour' (magenta is a shade of purple). I am not sure about the 'dark' bit.
'new game and books a' is the wordplay.
'new' indicates anagramming the letters.
'and' means one lot of letters go next to another.
'books' becomes 'NT' (New Testament).
'game' with letters rearranged gives 'mage'.
'mage'+'nt'+'a'='MAGENTA'
Can you help me to learn more?
(Other definitions for magenta that I've seen before include "Light mauvish-crimson" , "Purplish-red - battle" , "puce" , "Colour named after a bloody 1859 battle in Italy" , "Shade of purple" .)