Leaving diamonds in place of work (6)
I believe the answer is:
office
'place of work' is the definition.
(I've seen this before)
'leaving diamonds' is the wordplay.
'leaving' becomes 'off' ('I'm off' means 'I'm leaving').
'diamonds' becomes 'ice' (slang term for diamonds).
'off'+'ice'='OFFICE'
'in' acts as a link.
(Other definitions for office that I've seen before include "Workplace for white-collar workers" , "Place for administrative business" , "Position, or building in which colours in layers" , "Business room - position of responsibility or duty" , "Workplace for clerks" .)