Left by Ann, oil mixed with wool fat (7)
I believe the answer is:
lanolin
'wool fat' is the definition.
(synonyms)
'left by ann oil mixed' is the wordplay.
'left by' becomes 'l' (I've seen this in other clues).
'mixed' is an anagram indicator.
'ann'+'oil'='annoil'
'annoil' anagrammed gives 'anolin'.
'l'+'anolin'='LANOLIN'
'with' acts as a link.
(Other definitions for lanolin that I've seen before include "something on the Fleece" , "Oil extracted from wool" , "Grease on sheep's wool" , "substance found in ointments" , "Wool fat used in ointments" .)