I would like to ask if its possible to retain the email of my domain to godaddy and is hosted in gmail but the hosting is in different provider like namecheap. I know how to point the nameserver of namecheap to godaddy but my problem is with the email
Assuming I understand correctly, you are using Google Apps For Mail. If so, you may simply host your domain name with Namecheap and then set up Google MX records for your domain name. This way you will have your domain hosted with Namecheap and mail service handled by Gmail. No need to include GoDaddy into this chain.
You may find MX records here: https://support.google.com/a/answer/33915?hl=en
These MX records should be set up in your cPanel (if you have a hosting plan) or at the Advanced DNS page of your Namecheap account (if you are using Namecheap's Premium or Basic DNS).