Design on paper with name placed in a box (9)
I believe the answer is:
watermark
'name placed in a box' is the definition.
I can't judge whether this defines the answer.
'design on paper with' is the wordplay.
'design' becomes 'mark' (mark is a kind of design).
'on' means one lot of letters go next to another.
'paper with' becomes 'water' (I am not sure about this - if you are sure you should believe this answer much more).
'mark' put after 'water' is 'WATERMARK'.
Can you help me to learn more?
(Other definitions for watermark that I've seen before include "Line showing maximum flood level" , "Design in paper" , "Security device, on paper" , "Paper manufacturer's identification" , "faint pattern" .)