Lacking energy, attempted to reverse malicious gossip (4)
I believe the answer is:
dirt
'malicious gossip' is the definition.
(synonyms)
'lacking energy attempted to reverse' is the wordplay.
'lacking' is a deletion indicator.
'energy' becomes 'e' (physics symbol as in E=mc2).
'attempted' becomes 'tried' ('try' can be a synonym of 'attempt').
'to reverse' says the letters should be written in reverse.
'tried' with 'e' taken away is 'trid'.
'trid' back-to-front is 'DIRT'.
(Other definitions for dirt that I've seen before include "Obscenity" , "Grime - scandal" , "scandalous gossip" , "Scandalous info; earth" , "Grime - or controversial retention tax" .)