Sounds like you are trying to access the Clientless VPN hosted on the external ASA interface from the LAN network?
If that is the case then is there a real need to use from the internal LAN network?
It might be the case that you have not enabled this VPN on the internal interface of the ASA.
Yes, I want to get access to Clientless from the local network by connecting to an external ip address ASA.
I believe that this is not possible?
need to turn on Clientless on the internal interface and configure dns?
I agree with Jouni on this why would you need to establish VPN for internal resources when you can directly access them internally. Logically that defeats the purpose of VPN.
To add if you want to access Clientless VPN from internal network, you would need to enable it on internal interface. External interface wont give you the requisite.
Hope it helps.