Lockjaw (7)
I believe the answer is:
tetanus
'lockjaw' is the definition.
(I know that lockjaw can be written as tetanus)
This is the entire clue.
(Other definitions for tetanus that I've seen before include "Infection from wound" , "Disease causing muscular spasms" , "infectious disease" , "Attunes (anag) - muscular illness" , "Infection of the central nervous system" .)