Thwart (9)
'thwart' is the definition.
(I know that thwart can be written as foil)
This is all the clue.
(Other definitions for foil that I've seen before include "Check" , "shiny paper" , "Queer" , "Frustrate - light sword" , "Blunt sword with a button on the end" .)
'thwart' is the definition.
(I know that thwart is a kind of prevent)
This is the entire clue.
(Other definitions for prevent that I've seen before include "Avert, hinder" , "Stop (an action)" , "Stop, avert" , "Obviate" , "Stop, hinder" .)
'thwart' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for scupper that I've seen before include "dish" , "Ruin, put paid to" , "Hole for draining" , "Thwart" , "foil" .)
'thwart' is the definition.
(I know that thwart can be written as frustrate)
This is all the clue.
(Other definitions for frustrate that I've seen before include "Thwart or baffle" , "Prevent (plan) from being fulfilled" , "Prevent from progressing" , "'Thwart, disappoint (9)'" , "Put a stop to" .)
'thwart' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for stymie that I've seen before include "Block; hinder" , "Situation from which it is almost impossible to proceed" , "Hinder, obstruct, thwart" , "Obstruct as on putting green" , "Block or thwart, as on golf course" .)
(Other definitions for derail that I've seen before include "Cause to run off the tracks" , "Cause to come off the tracks" , "go off track" , "create an obstructive diversion" , "go off line" .)