Crossword Genius

Chromatic element of my prior ocular failing (fragmentary lights in rows) (7,6)

Ross

I believe the answer is:

primary colour

I'm a little stuck... Click here to teach me more about this clue!

'chromatic element' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'my prior ocular failing fragmentary lights in rows' is the wordplay.
'my prior ocular' can be anagrammed to 'PRIMARY COLOUR'.
But, I'm unsure how the anagram is indicated.

'of' acts as a link.

Can you help me to learn more?

I've seen this clue in The Independent.
Want a hint initially instead of a full solution? Install my app