End lies about oil source (7)
I believe the answer is:
linseed
'oil source' is the definition.
(I've seen this in another clue)
'end lies about' is the wordplay.
'about' indicates anagramming the letters.
'end'+'lies'='endlies'
'endlies' is an anagram of 'LINSEED'.
(Other definitions for linseed that I've seen before include "Treatment for bats" , "Source of plant oil" , "Oil-producing plant" , "Flax plant product providing oil" , "Enisled (anag.)" .)