Is it possible I can claim CLAM from coinbase address.
It is possible if and only if you have the private key for the address. I don't know if Coinbase will give you the private key or not. Alternatively Coinbase could claim the CLAM on your behalf and share it with you. You would have to talk to them about that.
I tried this site to check
https://freebitcoins.com/clamchecker/dig/ but it's saying my account not eligible.
Even I had my wallet address before then may 2014. I don't think Coinbase either give me private keys or will claim clam for me.