Cross king with nothing on sandwiches (6)
I believe the answer is:
narked
'cross' is the definition.
(I've seen this before)
'king with nothing on sandwiches' is the wordplay.
'king' becomes 'R' (abbreviation of Latin rex).
'with nothing on' becomes 'naked' (wearing no clothing).
'sandwiches' indicates putting letters inside (inserted letters are sandwiched in).
'r' placed within 'naked' is 'NARKED'.
(Other definitions for narked that I've seen before include "Cross" , "Nettled" , "Annoyed - upset - irritated" , "'Vexed, riled (6)'" , "Annoyed (informal)" .)