Cutting tool used to be returned (3)
I believe the answer is:
Here is my best explanation:
'cutting tool' is the definition.
(I've seen this before)
'used to be returned' is the subsidiary indication.
'used to be' becomes 'was' (I've seen this before).
'returned' is a reversal indicator.
'was' in reverse letter order is 'saw'.
(Other definitions for saw that I've seen before include "Adage", "Spotted", "Observed; tool", "Perceived visually", "Wood-cutting tool", "hand tool", "Was turned into a cutting tool", "item in tool kit", "Old saying - cutting kind" and "Implement for cutting wood".)