Thanks detective engaged by South America for sporting venues (6)
I believe the answer is:
stadia
'sporting venues' is the definition.
(plural of 'stadium')
'thanks detective engaged by south america' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'detective' becomes 'di' (Detective Inspector abbreviation).
'engaged by' is an insertion indicator (I've seen this in other clues).
'south america' becomes 'SA' (abbreviation).
'ta'+'di'='tadi'
'tadi' going inside 'sa' is 'STADIA'.
'for' acts as a link.
(Other definitions for stadia that I've seen before include "Sports grounds" , "major venues" , "large arenas" , "Large sports venues" , "Sports arenas" .)