Dissident is present with twitch (7)
I believe the answer is:
heretic
'dissident' is the definition.
(I know that heretic is a type of nonconformist)
'present with twitch' is the wordplay.
'present' becomes 'here' (both can mean in attendance).
'with' means one lot of letters go next to another.
'twitch' becomes 'tic' (tic is a kind of twitch).
'here'+'tic'='HERETIC'
'is' is the link.
(Other definitions for heretic that I've seen before include "One who holds opinions contrary to accepted religious beliefs" , "Cheer it (anag.)" , "Person of unorthodox beliefs" , "I wrongly believe" , "One breaking with orthodox beliefs" .)