Defender has constant luck with hard drop behind players (9)
I believe the answer is:
backcloth
'drop behind players' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'defender has constant luck with hard' is the wordplay.
'defender' becomes 'back' (left-backs and right-backs are football defenders).
'has' is a charade indicator (letters next to each other).
'constant' becomes 'c' (mathematical abbreviation).
'luck' becomes 'lot' (synonyms).
'with hard' becomes 'h' (abbreviation used in pencil classifications. I am not sure about the 'with' bit.).
'back'+'c'+'lot'+'h'='BACKCLOTH'
Can you help me to learn more?
(Another definition for backcloth that I've seen is " it's behind the scenes".)