Paper cross worn by one closing coffee morning (4)
I believe the answer is:
exam
'paper' is the definition.
(I've seen this before)
'cross worn by one closing coffee morning' is the wordplay.
'cross worn by one closing coffee' becomes 'ex' (I can't explain this - if you can you should believe this answer much more).
'morning' becomes 'am'.
'ex'+'am'='EXAM'
Can you help me to learn more?
(Other definitions for exam that I've seen before include "End-of-course assessment" , "Students sit it" , "Scholastic test" , "Written test" , "School test (colloq.)" .)