A Hebraic drink with degree of acidity (5)
I believe the answer is:
aleph
'a hebraic' is the definition.
(Hebrew equivalent of the letter A)
'drink with degree of acidity' is the wordplay.
'drink' becomes 'ale' (ale is a kind of drink).
'with' means one lot of letters go next to another.
'degree of acidity' becomes 'pH' (as in the pH scale of acidity in chemistry).
'ale'+'ph'='ALEPH'
(Other definitions for aleph that I've seen before include "First character" , "Abroad, a" , "First letter of the Hebrew alphabet" , "letter in Middle East" , "Sign of a beast? A Phoenician" .)