Some noticeable muscular spasm (3)
I believe the answer is:
tic
'muscular spasm' is the definition.
(I've seen this in another clue)
'some noticeable' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'TIC' can be found hidden inside 'noticeable'.
(Other definitions for tic that I've seen before include "Involuntary habitual response" , "Muscular contraction" , "Spasmodic muscular twitch" , "Muscle twitch" , "jerk" .)