Investments left on paper (9)
I believe the answer is:
portfolio
'investments' is the definition.
(I've seen this before)
'left on paper' is the wordplay.
'left' becomes 'port' (left side of a ship - opposite of starboard).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'paper' becomes 'folio' (folio is a kind of paper).
'port'+'folio'='PORTFOLIO'
(Other definitions for portfolio that I've seen before include "Set of papers" , "Carrying case for documents" , "Flat case for paper sheets" , "Set of investments held by one person" , "Minister's responsibility" .)