Use a different ssh key for a specific github organization

ssh-config

# ~/.ssh/config
Match host github.com exec "[[ $(git remote get-url origin | sed 's/^.*://' | sed 's/\/.*//') = TheGithubOrganization ]]"
    # Don't forget to ssh-add this in addition to other keys, or git will pick one that's already in the agent first
    IdentityFile ~/.ssh/specific_rsa

Nice but I assume this wont handle git clone ?

You're right - the answer on stack overflow linked above using gitconfig handles that though