Ready for seizure (3)
I believe the answer is:
fit
This clue is a double definition.
'ready' is the first definition.
(I've seen this before)
'seizure' is the second definition.
(I know that seizure can be written as fit)
'for' is the link.
(Other definitions for fit that I've seen before include "Sudden attack,of coughing say" , "Be the right size or shape" , "Suitable; healthy" , "Paroxysm" , "In trim" .)