SPI slave without MISO pin
Is it possible to use SPI bus like that with route only 3 pins?


For sure. Many devices need only data from the master and do what they have to do without conferring with the master. I can think of DAC devices that produce an analogue output with just the data collected from the SPI bus. Some will communicate back to the master but only usually when setting up the registers of more complex devices; for a simple DAC, MISO is usually omitted: -



Digipots have a similar story; they mostly don't have MISO: -