Office workers with mediocre investment in retirement plans (7)
I believe the answer is:
schemes
'plans' is the definition.
(scheme is a kind of plan)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for schemes that I've seen before include "Plans, plots, projects" , "''The best-laid ... o' mice an' men Gang aft a-gley''" .)