Relief of sorts as drivers receiving a single supply (9)
I believe the answer is:
analgesia
'relief of sorts' is the definition.
(pain relief)
'drivers receiving a single supply' is the wordplay.
'drivers' becomes 'aa' (Automobile Association).
'receiving' is an insertion indicator.
'supply' indicates anagramming the letters (in a supple way).
'a'+'single'='asingle'
'asingle' with letters rearranged gives 'nalgesi'.
'aa' going around 'nalgesi' is 'ANALGESIA'.
'as' acts as a link.
(Other definitions for analgesia that I've seen before include "Inability to feel pain" , "painless" , "The relief of pain by drugs" , "As a linage (anag) - insensibility to pain" , "Painlessness" .)