Briefly served up another drink one left in can for ages (5)
I believe the answer is:
lifer
'can for ages' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'briefly served up another drink one left' is the wordplay.
I cannot quite see how this works, but
'another' could be 'r' (I've seen this in other clues) and 'r' is found in the answer.
'one' could be 'i' (Roman numeral) and 'i' is found within the answer.
'left' could be 'l' (common abbreviation) and 'l' is found within the answer.
The remaining letters 'fe' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'in' acts as a link.
Can you help me to learn more?
(Other definitions for lifer that I've seen before include "Long-term prisoner" , "Serious criminal" , "Person serving long sentence" , "Prisoner serving the maximum term" , "One with very long sentence" .)