Coercion has Don going round the bend (6)
I believe the answer is:
duress
'coercion' is the definition.
(under duress means being coerced)
'don going round the bend' is the wordplay.
'don' becomes 'dress' (to don something is to dress in it).
'going round' is an insertion indicator (some letters go around others).
'the bend' becomes 'U' (a U-bend is a kind of bend - pipe under sink).
'dress' enclosing 'u' is 'DURESS'.
'has' is the link.
(Other definitions for duress that I've seen before include "The use of force or threats to get one's way" , "Restraint" , "Illegal coercion" , "Compulsion by use of force" , "Constraint, Compulsion" .)