Update:
the problem seems to get worse. I had this car since 11 years and put 200 000 km on the clock. Stopped at a traffic light, putting it in 2nd (which is easy to do) and then going back to 1st gear does not always help. If the car is on a downward slope, letting it roll for half a turn of wheels and then engaging 1 st often helps, even if I had to stop again. I believe the problem progressively became worse during the last 6 months, which means during the last 10 000 km.
I read some posts on the forum, the discussion goes like: maybe a bearing issue (clutch bearing?), maybe a synchro issue. I am not sure what it is.
This car has a hydraulic clutch.
Before buying the Abarth in 2011, I did drive a Fiat Bravo S, from 1996 to 2011, that car had a mechanical clutch. With the mechanical clutch, it also became difficult to engage first gear when it had about 160 000 km on the clock. I found the clutch cable to have some slack and tightened the play several times over the years until the clutch failed completely at about 250 000 km. The pedal started pumping by itself, first only when pressed and later all the time, as something must have broken inside the clutch.
I find it rather annoying that the clutch of my APE now apparently starts dying on me, too, without reason.