Looks like the cap is already removed but you would clip the end to let the glue flow.
Cut off the tip like a tube of caulk or use a small drill to drill it out.
I did. I tried forcing a pin into it with nearly all my might, bent the pin, that is it.
There is something in there that blocks the flow.
There is liquid cement in it, that’s obvious.
This is as far as it goes. It’s like hitting rock at this point.
EDIT: Okay, got it. I had to force the pin so hard I was breaking into a sweat. 
By the way, I noticed someone on another forum had the exact same problem.
Go Tamiya thin glue.
I had a bottle but it evaporated. 
You left the cap open I bet! Happens to me too.
The seal under the lid needs to be perfect and clean to prevent evaporation.
The older ones with the metal tube were easy to clear . Just flick your bic and it would burn out. This plastic tip looks like bad news to me
Someone on another forum mentioned this: plastic cap versions are very difficult to open.
This is the glue type and bottle that I have been using for indy link plastic track assembly for 30 years. It is the perfect dispenser and viscosity for it. Much more control than Tamiya Extra Thin and it doesn’t fully set up for an hour, so you can assemble a whole track run and bend it around the running gear to dry.
I’ve ran into this problem twice before with these plastic tipped bottles. Like you I’ve tried using a straightened safety pin but without success so far. The rolled up piece of copper wire that comes in the glue’s package actually has cleared a clog a couple of times. However, it proved totally USELESS with this current clog. I use these gel type glues to assemble link and length tracks. As SSGToms stated its’ slow setting time is optimal for making parts adjustments.
Cheers,
Jan 
Maybe using fire is the cure?! 