Oil producer's old tale about volume (5)
I believe the answer is:
olive
'oil producer's' is the definition.
(I've seen this in another clue)
'old tale about volume' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'tale' becomes 'lie' (I've seen this in another clue).
'about' means one lot of letters goes inside another.
'volume' becomes 'v' (abbreviation for volume in book titles).
'lie' placed around 'v' is 'live'.
'o'+'live'='OLIVE'
(Other definitions for olive that I've seen before include "Green shade; its branch for peace" , "Oil-yielding fruit" , "Fruit also used to make oil" , "Bitter fruit" , "Oily stone fruit" .)