Hi,
As you know that the SPI protocol does not use any handshaking signal, the spi master transmits/receives data from slave spi in a blind mode, the master spi receiver will receive 0xFFFF in 16 bits mode when the slaver spi is not connected generally.
In conclusion, there is not any way for the master spi to know if the slave spi device is connected or not, but as a trick, I think if you receive multiple 0xFFFF(if you do not receive 0xFFFF with slave spi device is connected, you can connect a pull-up resistor on the MISO pin), you see that slave is connected.
Hope it can help you
BR
XiangJun Rong