Speak without distinction in France on consuming litres (4)
I believe the answer is:
slur
'speak without distinction' is the definition.
(as in slurring one's speech)
'france on consuming litres' is the wordplay.
'france on' becomes 'sur' (I can't explain this - if you can you should give a lot more credence to this answer).
'consuming' means one lot of letters goes inside another.
'litres' becomes 'l' (abbreviation for litres).
'sur' going around 'l' is 'SLUR'.
'in' is the link.
Can you help me to learn more?
(Other definitions for slur that I've seen before include "Pronounce indistinctly - discredit" , "It's not clear, so to speak" , "Pronounce indistinctly or smear" , "Slight sound" , "Pronounce words indistinctly" .)