More work's work one placed in out-tray occasionally (6)
I believe the answer is:
utopia
'more work's' is the definition.
(work by Sir Thomas More)
'work one placed in out-tray occasionally' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'one' becomes 'i' (Roman numeral).
'placed in' means one lot of letters goes inside another (I've seen this in other clues).
'occasionally' indicates alternate letters (letters taken at regular intervals or occasions).
'out'+'tray'='outtray'
The alternating letters of 'outtray' are 'uta'.
'op'+'i'='opi'
'opi' put into 'uta' is 'UTOPIA'.
(Other definitions for utopia that I've seen before include "Eden" , "Place of ideal perfection" , "More's imaginary state" , "Imaginary ideal place" , "Place of perfect happiness" .)