This thread is old as dirt but I came upon same issue when sourcing a clip for an 2010 camaro SS slave cylinder.
At GM as stated above the whole assembly does need to be bought but apparently there is a VW slave cylinder line and FORD slave cylinder line clip that is identical.
VW OEM Part # 7M0721431
FORD(european) Part # 4560608
I'll reply again with confirmation once I visit dealerships tomorrow unless this is a nonissue.