True lassis regularly used herb (5)

I believe the answer is:

tulsi

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'herb' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'true lassis regularly' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'true'+'lassis'='truelassis'
The alternate letters of 'truelassis' are 'TULSI'.

'used' acts as a link.

Can you help me to learn more?

I've seen this clue in The Hindu.

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