Beer made with old plant (4)
I believe the answer is:
aloe
'plant' is the definition.
The answer is an example.
'beer made with old' is the wordplay.
I cannot quite understand how this works, but
'old' could be 'o' (common abbreviation eg in OE for Old English) and 'o' is found in the answer.
'beer' could be 'ale' (type of beer) and 'ale' is found in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for aloe that I've seen before include "has a bitter taste" , "Genus of bitter herbs" , "O, ale with bitter plant" , "Bitter fruit" , "Fleshy-leaved plant" .)