Malware gets rid of evidence of underground activity? (9)
I believe the answer is:
wormcasts
'malware gets rid of evidence of underground' is the definition.
I can't tell whether this definition defines the answer.
'activity?' is the wordplay.
I cannot quite understand how this works, but
'activity?' could be 'cast' (cast is a kind of activity) and 'cast' is present in the answer.
The remaining letters 'worms' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for wormcasts that I've seen is " lumps on the grass".)