It may come forth with the beer (5)
I believe the answer is:
froth
'the beer' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'it may come forth' is the wordplay.
'forth' can be anagrammed to 'FROTH'.
Though, I am not sure how the anagram is indicated.
'with' is the link.
Can you help me to learn more?
(Other definitions for froth that I've seen before include "Spume or foam" , "Mass of small bubbles" , "Effervesce" , "Lather" , "Small bubbles on a liquid" .)