Some ground offered in ruin (4)
I believe the answer is:
undo
'ruin' is the definition.
(someone's undoing is their ruin)
'some ground offered in' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'UNDO' is hidden within 'ground offered in'.
(Other definitions for undo that I've seen before include "Cause the ruin of, or cancel" , "Open, a knot say" , "Open button or ruin" , "Loosen (knot)" , "Cancel, annul; open" .)