What? Legally? Who's talking about legally? Obviously, anything of the sort would be illegal as per international law.
A 'tough covert op' doesn't work that way. If you're talking about sending India's supa dupa pawa stealth helicopters and commandos, well
If you're talking about sending undercover operatives to Karachi, finding Dawood Ibrahim, capturing him alive and dragging him to India covertly, well, it's more realistically possible but still very, very unlikely. And if all of India's claims are true, you'll also have the almighty ISI to deal with.