It's a bit convoluted Compo but I think it goes something like this.
Endless racket = Frau(d) -correct from Mamya
with = added to (which can sometimes mean 'on the end' or following
tip of Alpenhor(n)
being banged up here (allusion to prison= jug - and the 'n' being imprisoned in the Ju(n)g
Then the second half of the clue acts as a &lit with the Def being 'Alpenhorn being banged up here'
A little bit vague, but see what you think