On returning, wasn’t keeping a single tool (5,3)
I believe the answer is:
tenon saw
'tool' is the definition.
(I've seen this before)
'on returning wasn't keeping a single' is the wordplay.
'on returning' says the letters should be written backwards.
'keeping' is an insertion indicator (some letters kept inside).
'a single' becomes 'one' (a single thing - only one).
'wasnt' going around 'one' is 'wasnonet'.
'wasnonet' reversed gives 'TENON-SAW'.
(Other definitions for tenon saw that I've seen before include "Woodcutter" , "used in joint production" , "Tool used for making wooden joints - wants one (anag)" , "Carpenter's tool" , "Precision cutter for making wooden joints" .)