In ruin I leave nothing (3)
I believe the answer is:
nil
'nothing' is the definition.
(eg nil is zero in football)
'in ruin i leave' is the wordplay.
'in' indicates a hidden word.
'NIL' is hidden within 'ruin i leave'.
(Other definitions for nil that I've seen before include "Zero, no score" , "Nix, nada, nothing" , "Latin zero" , "Nothing found in senility" , "none" .)