Shiftin with external Clock howto ?

[RFsolution]

Hi

I have a hardware situation where I need to read a 12bit serial output
clocked by his own clock

If i'm right all Shiftin commands generates an own clock signal
is there a way to use an external clock with some sort of shiftin

When the chipselect pin goes low, the clock is present and starts sending the 12bits
once finished Chipselect goes high etc...

Any help welcome