Unnatural movement caused by sulphur in processed meat (5)
I believe the answer is:
spasm
'unnatural movement' is the definition.
'spasm' can be an answer for 'movement' (I have seen 'sudden movement' mean 'spasm' so perhaps 'movement' could also mean 'spasm'). I am not certain of the 'unnatural' bit.
'sulphur in processed meat' is the wordplay.
'sulphur' becomes 'S' (synonyms).
'in' indicates putting letters inside.
'processed meat' becomes 'sp am' (I've seen this before).
's' placed inside 'spam' is 'SPASM'.
'caused by' acts as a link.
Can you help me to learn more?
(Other definitions for spasm that I've seen before include "Tic, sudden contraction" , "Pretend to have (injury)" , "Muscle twitch" , "Involuntary muscular movement" , "Muscular convulsion" .)