A good ground halved trouble (5)
I believe the answer is:
aggro
'trouble' is the definition.
(I've seen this before)
'a good ground halved' is the wordplay.
'a good' becomes 'ag' (I've seen this in other clues).
'halved' indicates taking half.
'ground' halved is 'gro'.
'ag'+'gro'='AGGRO'
(Other definitions for aggro that I've seen before include "Aggressive, violent behaviour in short" , "Belligerent trouble" , "Difficulties (sl.)" , "Slang for deliberate trouble-making" , "belligerence" .)