Crossword Genius

Relative’s Greek letter brought in after I removed sculpted granite (5,4)

Ross

I believe the answer is:

great aunt

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

'relative's' is the definition.
(great-aunt is a kind of relative)

'greek letter brought in after i removed sculpted granite' is the wordplay.
I cannot quite understand how this works, but
'greek' could be 'gr' and 'gr' is present in the answer.
'letter' could be 'tau' (tau is a kind of letter of the alphabet) and 'tau' is found within the answer.
'i' could be 'a' and 'a' is located in the answer.
This may be the basis of clue (or it may be nonsense).

Can you help me to learn more?

(Other definitions for great aunt that I've seen before include "elderly relative" , "Female earlier in line" , "Relation" , "Old lady" .)

I've seen this clue in The Hindu.
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