27 down is linked to a theme which is Oktoberfest in Glasgow, so it’s an anagram of letters LEGS ARCH which I’ve taken to be the brass instrument the schagerl. But the a does not fit with a clue going across which I’ll give you - it’s “after drink , harass six footer for drug” which I take to be suppressant and the a would be the fifth letter not the fourth in schagerl.
Then there is 42 across which is 9 letters and it’s “like supermarket items left among stray bean cans”. I’ve got
S?A???B??
If the schagerl is correct then the last letter should be an R