It is prostate liquid which is clear and easy to believe it is precum.I love to edge and usually practice 60-90 minutes each morning while my wife is still asleep. I love feeling the precum rise through my urethra and start leaking out my slit. I enjoy the feeling of wetness as it oozes out although I'm not a big precummer.
On rare occasions when I play, I've been able to produce a LARGE amount of what I assume to be Cowper's Gland fluid - an amount equal to a normal ejaculation for me. It is completely clear and VERY slippery. This has happened when I've done external prostate massage while playing with my semi-hard cock. Once that leaked out, I used it as lube to jackoff to completion. It was as good or better than any lube I've ever used. And, it definitely was not urine as I taste-tested it.
As i posted before it is common on people who edge (you are having a lot of fun which makes your prostate build more liquid than common, and it has to be released. It happens when you are more horny than common and/or having more fun).
I bet when you cum, it looks more watery. It is ok, simply it has more prostate liquid than commonly.
As you said stimulating the prostate is also other way to build more and make it be released.
For ending if you rubb intensly your cock head, where you peehole, you can make it happens.
Enjoy it!