Writ commanding court attendance (8)
I believe the answer is:
subpoena
'writ commanding court attendance' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for subpoena that I've seen before include "Writ ordering court apperarance about bean soup" , "Attendance-requiring writ" , "Summons follows!" , ""Under penalty" (Latin)" , "Writ to compel a witness to attend court" .)