'Clarence' was an Allied special forces operation by the Special Operations Executive to parachute a three-man Dutch and US 'Jedburgh' team into the Groesbeek area of the German-occupied Netherlands to support 'Market' by the establishment of contact with the local elements of the Dutch resistance movement (17 September 1944 onward).
Three related SOE efforts at the same time were 'Edward', 'Claude' and 'Daniel'.