Empty space left in repository (5)
I believe the answer is:
blank
'empty space' is the definition.
(I've seen this before)
'left in repository' is the wordplay.
'left' becomes 'l' (common abbreviation).
'in' is an insertion indicator.
'repository' becomes 'bank' (bank is a kind of repository).
'l' inserted into 'bank' is 'BLANK'.
(Other definitions for blank that I've seen before include "Vacuous" , "Void (of writing, thought, etc)" , "Space left to be filled" , "Expressionless" , "Bare; not decorated" .)