Accumulation of jobs not done (7)
I believe the answer is:
backlog
'accumulation of jobs not done' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for backlog that I've seen before include "Accumulation of jobs not done" , "Accumulation (of work) to be dealt with" , "An arrear as of work" , "work not yet completed" , "Quantity of work still to be done" .)