Letter showing the acidity of beer? (5)
I believe the answer is:
aleph
'letter' is the definition.
(letter of the Hebrew alphabet)
'the acidity of beer?' is the wordplay.
I cannot really understand how this works, but
'acidity' could be 'ph' and 'ph' is found within the answer.
'beer?' could be 'ale' (type of beer) and 'ale' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'showing' acts as a link.
Can you help me to learn more?
(Other definitions for aleph that I've seen before include "First character" , "Hebrew character" , "letter in Middle East" , "Sign of a beast? A Phoenician" , "Abroad, a" .)