Knight outspoken on cafe's putrid benchtops (8)
I believe the answer is:
surfaces
'benchtops' is the definition.
I can't judge whether this defines the answer.
'knight outspoken on cafe's putrid' is the wordplay.
'knight' becomes 'sir' (a knight has the title Sir).
'outspoken' indicates a 'sounds like' (homophone) clue (as the word might be spoken).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'cafe's putrid' becomes 'faces' (I can't justify this - if you can you should give a lot more credence to this answer).
'sir' sounds like 'sur'.
'sur'+'faces'='SURFACES'
Can you help me to learn more?
(Other definitions for surfaces that I've seen before include "Upper or outer sides" , "They have length and breadth only" , "planes - with 23a" , "Comes to light or rises to the top" , "The outsides of objects" .)