Spare balls help when covers are taken off in match (8)

I believe the answer is:

parallel

'match' is the definition.
(I've seen this before)

I don't understand how the remainder of the clue works.

(Other definitions for parallel that I've seen before include "Analogy; line of latitude" , "The 49 th - separates the US from Canada" , "Circle of constant latitude" , "Analogue; similarity" , "Side by side" .)

I've seen this clue in The Independent.

Want a hint initially instead of a full solution? Install my app