Protest against work singular Gothic writer pens (6)
I believe the answer is:
oppose
'protest' is the definition.
(I know that protest is a more specific form of oppose)
'against work singular gothic writer pens' is the wordplay.
'against' says to put letters next to each other.
'work' becomes 'op' (abbreviation for opus).
'singular' becomes 's' (abbreviation in grammar).
'gothic writer' becomes 'Poe' (Edgar Allan Poe).
'pens' indicates putting letters inside (to pen can mean to contain or imprison).
's' going into 'poe' is 'pose'.
'op'+'pose' is 'OPPOSE'.
(Other definitions for oppose that I've seen before include "Resist, be hostile to" , "Counter" , "Resist; play against" , "Compete with" , "Bar" .)