Brought up a block of wood (5)
I believe the answer is:
balsa
'wood' is the definition.
(balsa is a kind of wood)
'brought up a block' is the wordplay.
'brought up' is a reversal indicator (down clues only).
'block' becomes 'slab' (slab is a kind of block**).
'a'+'slab'='aslab'
'aslab' back-to-front is 'BALSA'.
'of' is the link.
(Other definitions for balsa that I've seen before include "South American tree" , "Very light timber" , "Tree with light soft wood" , "A slab (anag.)" , "Tropical American tree" .)