Worker was returning tool (7)
I believe the answer is:
handsaw
'tool' is the definition.
(handsaw is a kind of tool)
'worker was returning' is the wordplay.
'worker' becomes 'hand' (hand is a kind of worker).
'returning' says the letters should be written in reverse.
'was' reversed gives 'saw'.
'hand'+'saw'='HANDSAW'
(Other definitions for handsaw that I've seen before include "Manual tool" , "cutting tool" , "Manual cutter" , "wood tool" .)