Oxford inspector left mouthful (6)
I believe the answer is:
morsel
'mouthful' is the definition.
(morsel is a kind of mouthful)
'oxford inspector left' is the wordplay.
I cannot quite see how this works, but
'inspector' could be 'morse' (Inspector Morse) and 'morse' is found in the answer.
'left' could be 'l' (common abbreviation) and 'l' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for morsel that I've seen before include "Dainty" , "a little food" , "Crumb" , "Tiny piece" , "Scrap, fragment" .)