Mean storm follows hail (7)
I believe the answer is:
average
'mean' is the definition.
('average' can be a synonym of 'mean')
'storm follows hail' is the wordplay.
'storm' becomes 'rage' ('rage' can be a synonym of 'storm').
'follows' means one lot of letters go next to another.
'hail' becomes 'ave' (I've seen this before).
'rage' after 'ave' is 'AVERAGE'.
(Other definitions for average that I've seen before include "Normal amount" , "Middle value, the norm" , "'Medium, middling (7)'" , "Mean - medium" , "Normal; mean" .)