Runner showing increased complacency circling lake (8)
I believe the answer is:
smuggler
'runner' is the definition.
(run can mean to smuggle banned goods)
'showing increased complacency circling lake' is the wordplay.
'showing increased complacency' becomes 'smugger' (smug can mean complacent).
'circling' indicates putting letters inside (circling can mean going around or containing).
'lake' becomes 'l' (geographical abbreviation).
'smugger' placed around 'l' is 'SMUGGLER'.
(Other definitions for smuggler that I've seen before include "Criminal" , "Transporter of illegal goods" , "Exciseman's foe" , "One who imports or exports without paying duties" , "Importer of goods without paying duties" .)