Leaking radiator (with picture)

[Pillskii]

One of my radiators is leaking, albeit very slowly. I've attached a picture below, the water is dropping from the bottom of the nut. Now I'm not the most hands on, although I feel loath to call out a plumber for what, on the surface, looks like a tiny issue.

Can I just tighten the nut with a wrench and it will stop?

(Picture needs turned 90 degrees clockwise sorry)

[Pillskii]

Big Al. said:

The bottom of what nut left or right (attached to pipe) in the image?

It's the right hand nut further from the pipe, you can see the drip hanging off the bottom. Sorry it's not very clear!

I'll maybe give it a very slight tighten and see how it reacts. Got fears of water gushing out everywhere.