Fashion a slab of wood (5)
I believe the answer is:
balsa
'wood' is the definition.
(balsa is a kind of wood)
'fashion a slab' is the wordplay.
'fashion' indicates anagramming the letters.
'a'+'slab'='aslab'
'aslab' is an anagram of 'BALSA'.
'of' is the link.
(Other definitions for balsa that I've seen before include "Model makers use it" , "Strong lightweight wood" , "A slab (anag.)" , "light raft" , "Wood used in model making" .)