Yes, a WDS Radio can be used to for client connections. A separate WLAN Service must be configure for clients to connect to a SSID.
Clients will not be able to connect to the WDS WLAN service that is used between the Parent and Child AP.
Note: If possible, it is recommended that the radio configured for the WDS or Mesh connect is used for AP communication, and the other radio is configured for client traffic. This will maximize bandwidth for WDS and client traffic.