Pardeep - what does the cork look like? Maybe it's old and some of it has crumbled into your Cardhu. If this is the case, the spirit is fine. I doubt you'll be able to return it to a duty free shop, so you have nothing to lose. Cardhu is chill-filtered (chilled and passed through a fine filter) - so no reason to have any particles floating around.
Open it up and take a sip. Good luck.
