Police leader to pursue about lying (7)
I believe the answer is:
resting
'lying' is the definition.
('rest' can be a synonym of 'lie')
'police leader to pursue about' is the wordplay.
'police leader' becomes 'sting' (front-man of The Police).
'to pursue' says to put letters next to each other.
'about' becomes 're' (regarding**).
'sting' put after 're' is 'RESTING'.
(Other definitions for resting that I've seen before include "(Of actor) not working" , "(Of actors) currently unemployed" , "Actor while out of work" , "Lying down" , "Out of work (acting)" .)