Store turned over in coliseum (4)
I believe the answer is:
silo
'store' is the definition.
(a store of crops)
'turned over in coliseum' is the wordplay.
'turned over' shows that the letters should be reversed in order.
'in' says the answer is hidden in the clue.
'olis' is hidden in the letters of 'coliseum'.
'olis' reversed gives 'SILO'.
(Other definitions for silo that I've seen before include "Launch site" , "Grain store; missile site" , "Large container for oils" , "Storage space for fodder" , "Farm store; soil (anag.)" .)