Also coming through is a terrible darn storm (7)
I believe the answer is:
tornado
'storm' is the definition.
(tornado is a kind of storm)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for tornado that I've seen before include "Cyclone, twister" , "Violent whirlwind over land" , "Road not turned in the windstorm" , "Severe wind" , "Terrible current" .)