Monster repulsed in the course of terrible turbulence (5)
I believe the answer is:
brute
'monster' is the definition.
(I've seen this in another clue)
'repulsed in the course of terrible turbulence' is the wordplay.
'repulsed' shows that the letters should be reversed in order.
'in the course of' indicates a hidden word.
'eturb' can be found hidden inside 'terrible turbulence'.
'eturb' backwards is 'BRUTE'.
(Other definitions for brute that I've seen before include "Beast - "Et tu ____ !"" , "Caliban" , "Nasty person, a real beast" , "Solely physical" , "One monstrous" .)