Futile endeavour roughing up floor with sander (5,6)
I believe the answer is:
fools errand
'futile endeavour' is the definition.
The definition suggests a singular noun which matches the answer.
'roughing up floor with sander' is the wordplay.
'roughing up' indicates an anagram (I've seen this in other clues).
'with' says to put letters next to each other.
'floor' put after 'sander' is 'sanderfloor'.
'sanderfloor' anagrammed gives 'FOOLS ERRAND'.
Can you help me to learn more?
(Other definitions for fools errand that I've seen before include "Fruitless enterprise" , "Unsuccessful enterprise" , "Fruitless task" , "Fruitless undertaking" , "Hopeless task" .)