Bring back a slab of wood (5)
I believe the answer is:
balsa
'wood' is the definition.
(type of wood)
'bring back a slab' is the wordplay.
'bring back' says the letters should be written in reverse.
'a'+'slab'='aslab'
'aslab' in reverse letter order is 'BALSA'.
'of' is the link.
(Other definitions for balsa that I've seen before include "Wood used by model makers" , "Very light wood in a slab" , "wood for raft" , "Very lightweight wood from tropical tree" , "Tree yielding light wood" .)