Screen ambassador holding papers (4)
I believe the answer is:
hide
'screen' is the definition.
(hide can mean to screen or cover up)
'ambassador holding papers' is the wordplay.
'ambassador' becomes 'HE' (His or Her Excellency).
'holding' indicates putting letters inside.
'papers' becomes 'ID' (identification papers).
'he' placed around 'id' is 'HIDE'.
(Other definitions for hide that I've seen before include "Not show" , "Fell" , "Keep quiet" , "Conceal, veil" , "Conceal - skin" .)