Jerky movement made by tense sorceress (6)
I believe the answer is:
twitch
'jerky movement' is the definition.
(I've seen this before)
'by tense sorceress' is the wordplay.
'by' says to put letters next to each other.
'tense' becomes 't' (abbreviation used in many dictionaries).
'sorceress' becomes 'witch' (I've seen this before).
't'+'witch' is 'TWITCH'.
'made' acts as a link.
(Other definitions for twitch that I've seen before include "Short, jerky motion" , "Spasmodic muscle contraction" , "Nervous action" , "Move spasmodically" , "involuntary response" .)