Grasp the mark indicating one of the possible horizontal directions (7,5)

I believe the answer is:

compass point

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'one of the possible horizontal directions' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.

'grasp the mark' is the wordplay.
'grasp' becomes 'compass' (synonyms).
'the mark' becomes 'point' (point is a kind of mark).
'compass'+'point'='COMPASS POINT'

'indicating' acts as a link.

Can you help me to learn more?

I've seen this clue in The Hindu.

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