Lying about fraudulent activity (7)
I believe the answer is:
resting
'lying' is the definition.
('rest' can be a synonym of 'lie')
'about fraudulent activity' is the wordplay.
'about' becomes 're' (regarding).
'fraudulent activity' becomes 'sting' (sting is a kind of activity. I am not sure about the 'fraudulent' bit.).
're'+'sting'='RESTING'
Can you help me to learn more?
(Other definitions for resting that I've seen before include "Lying down" , "Reposing" , "At ease" , "Taking it easy" , "Out of work (acting)" .)