Bet here when coin thrown about (6)
I believe the answer is:
casino
'bet here' is the definition.
(a place for betting)
'when coin thrown about' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'thrown' is an anagram indicator.
'about' means one lot of letters goes inside another.
'coin' with letters rearranged gives 'cino'.
'as' placed inside 'cino' is 'CASINO'.
(Other definitions for casino that I've seen before include "Where some gamblers go" , "where one can lose a lot of money" , "Gambling den" , "Building for gambling" , "gambling joint" .)