Spasms that almost give you a stiff back (4)
I believe the answer is:
fits
'spasms' is the definition.
The answer and definition can be both states of affairs as well as being plural nouns.
Perhaps there's a link between them I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for fits that I've seen before include "Is of the right shape and size" , "Paroxysms" , "crises once" , "short bouts" , "Seizures" .)