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 cannot see how one could define the other.
'briefly served up another drink one left' is the wordplay.
I cannot really 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 located in the answer.
'left' could be 'l' (common abbreviation) and 'l' is found in the answer.
The remaining letters 'fe' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'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" .)