Crossword Genius

Drug variant developed with involvement of international labs, primarily (9)

Ross

I believe the answer is:

antiviral

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

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

'variant developed with involvement of international labs primarily' is the wordplay.
I cannot quite understand how this works, but
'international' could be 'i' (abbreviation eg in IMF) and 'i' is present in the answer.
an anagram of 'variant' is 'antvira' which is within the left over letters.
A single letter 'l' remains which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).

Can you help me to learn more?

(Other definitions for antiviral that I've seen before include "Like interferons" , "describing security software?" , "Drug" , "inhibiting disease" .)

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