I am trying to get a Ad approved which contains word 'Craigslist'. The Ad is under review but I doubt that the Google would approve these Ads. When I put 'Craigslist's' then it don't show copyright notice. Will Adword approve my ad containing word 'Craigslist's'? If not then help me with getting my Ad approved by tweaking the Ad.
Craigslist is a trademark (different from copyright, but most people confuse them). If Craigslist has asked Google to not show their trademark in ads, and chances are they have, there's nothing you can do. You will need to word your ads more generically without specifically mention Craigslist.
I have protected keywords on adwords right now. Google will contact the person who owns the trademark and ask them if it's ok IF you request an exception. If you don't ,then they just won't show it by default.