Pen, pound (9)
I believe the answer is:
enclosure
I believe this is a double definition.
'pen' is the first definition.
(I've seen this before)
'pound' is the second definition.
(I've seen this before)
(Other definitions for enclosure that I've seen before include "Document included with a letter" , "pound" , "Area fenced off - one's ulcer (anag)" , "What's in the envelope" , "One's contained" .)