One is up after an ale about midnight for relief from pain (9)
I believe the answer is:
analgesia
'relief from pain' is the definition.
'analgesia' can be an answer for 'relief' (I have seen 'Relief of pain ' mean 'analgesia' so perhaps 'relief' could also mean 'analgesia'). I am not sure about the 'from pain' bit.
'one is up after an ale about midnight' is the wordplay.
I cannot really see how this works, but
'one' could be 'an' (an apple is one apple) and 'an' is located in the answer.
'an' could be 'i' (Roman numeral for one) and 'i' is found within the answer.
'about' could be 'a' (abbreviation in Chambers) and 'a' is located in the answer.
'midnight' could be 'g' (the middle letter in 'night') and 'g' is located in the answer.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?
(Other definitions for analgesia that I've seen before include "result of medication?" , "Loss of pain" , "No hard feelings" , "Painlessness" , "The relief of pain by drugs" .)