which clock for arduino

can I use a rasclock v4.2 - initially bought for a Raspberry Pi - with an Arduino Uno R3
to indicate date and time ?

Yes, although the PCF2129 isn't very common.

many thanks for this quick replay. What library should I use ?

I don't know, one that supports the chip. Or write your own. Like I said, hardware can work fine but the chip isn't very common.