i believe that if you have immo2 clocks or earlier then you can fit any mk4 clocks into it as only the immo3 ones have the immobiliser in the circuit, i have never tried this and don't know just how true it is but if you have any friends or family with a mk4 you could always try the clocks, just takes a min to remove them
as for the flickering, it the whole clocks on the wifes that flicker, if yours is just the fis then it may just need re securing, take the clocks out, remove the back, now on the circuit board there is a metal cage that will come off the board with the tist of some metal legs, if you search it on google there will be a guide of how to fix mk4 fis display as i used it for mine some time ago but have forgotten exactly how to do it
as for the clifford, it all depends on the fitter, the mk3 onwards was fitted with a factory immobiliser, some fitters use the standard immo wire in the aftermarket alarm to that others make use of the separate immo in the new unit this giving you 2 immobilisers in 1 car, it's highly unlikely that an after market immobiliser is the issue unless it's wire in to the factory unit, without checking the wiring of it all it's hard to say which way round it's been done