Well, this could be just a loose clamp... or a crack in the neck that
the hose goes over... not necessarily a bad hose.

If you do have to replace the hose, gunks and goos shouldn't be at all
necessary if you get the hose on there square and use quality hose
clamps of the right size, tightened properly.

As long as you're at it, consider the condition of the other hoses and
how long it's been since you changed the coolant. You don't mention I
like to just re-do all the hoses every several years as a preventive
maintenance item. They have a hard life in there. Might be a good
time to change the cap too.

Be sure to use the recommended coolant in more or less the right
mixture with water (preferably distilled or de-ionized, not tap water),
dispose of the old stuff in the way recommended by the city, and avoid
letting dogs and cats get at it.

Cheers,
--Joe