A black conductor stand (of which the audience would only see the black back) is going to be way more discreet than a bright white sheet of paper hanging off of a black mic stand!!!!
If you're really determined to hang the music off a mic stand, go to a place that sells computer stuff and check out the document holders that they sell for computer monitors. A bit of velcro and you should be able to secure it to a mic stand. Just ask for a document holder for your computer and they should know what you mean. Or, if you're broke, grab a chip clip thing (big plastic binder clip that you close the tops of the chip bags with) and zip tie it to the stand.
Since you referenced A5 paper, you're probably not over here in the states..... here the stores that carry the doc holders are places like Staples, Office Max/Depot, walmart may have one but it'll be cheap quality...not sure the names of the stores there
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You could put a piece of black paper behind the lyrics sheet if you do use the clip method so that the audience would just see the black piece of paper and not have any clue what was hanging there...
