is done on the VOR/DME, if this aid goes u/s
This isn't a single aid. It's two: A VOR and a DME.
Which one of these two do you mean when you fail the aid?
If the DME is the one then you can't fly the arc specified on the approach plate using another DME unless that other DME is specified as an alternative.
If the VOR is the failed aid then you could fly the arc however you may not be able to determine your position around the arc. This means that any azimuth related part of the procedure such as the IAF, minimum altitudes &/or lead radials become unuseable, having the practical effect of making the arc useless for the approach.
Unless of course an alternative azimuth aid is specified for the procedure.
Of course if BOTH fail then it's time the operator of the aid paid his electricity bill...
Aids that are available to be used in a procedure are determined by the procedure designer, not the pilot.