Completion of table leads to spare wood (5)
I believe the answer is:
ebony
'wood' is the definition.
(I know that ebony is a type of wood)
'completion of table leads to spare' is the wordplay.
'completion of' suggests the final letters.
'leads to' means one lot of letters go next to another.
'spare' becomes 'bony' (both can mean very thin).
The final letter of 'table' is 'e'.
'e'+'bony'='EBONY'
(Other definitions for ebony that I've seen before include "Tree having black wood" , "Wood - Boyne (anag)" , "Material for key" , "Hard dark-coloured wood" , "Black hardwood" .)