Clubs on that Man United ground (6)
I believe the answer is:
chewed
'ground' is the definition.
(chewing is a kind of grinding)
'clubs on that man united' is the wordplay.
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'on' says to put letters next to each other.
'that man' becomes 'he'.
'united' becomes 'wed' (I've seen this before**).
'c'+'he'+'wed'='CHEWED'
(Other definitions for chewed that I've seen before include "Worked or ground between the teeth" , "Masticated, worked with teeth" , "Made use of teeth" , "Masticated between teeth - maybe gum" , "Thought about" .)