Bishop in staggering movement, hero in act of defiance (9)
I believe the answer is:
rebellion
'act of defiance' is the definition.
'bishop in staggering movement hero' is the wordplay.
'bishop' becomes 'b' (abbreviation used in chess).
'in' means one lot of letters goes inside another.
'staggering movement' becomes 'reel'.
'hero' becomes 'lion'.
'b' going within 'reel' is 'rebel'.
'rebel'+'lion'='REBELLION'
'in' is the link.
(Other definitions for rebellion that I've seen before include "Insurgency" , "Boxers' movement" , "Defiance" , "Coup d'tat" , "Rising" .)