He splits a couple of poles made of wood (5)
I believe the answer is:
ashen
'made of wood' is the definition.
'he splits a couple of poles' is the wordplay.
'splits' means one lot of letters goes inside another (inserted letters split open the word).
'couple of poles' becomes 'sn' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a'+'sn'='asn'
'he' going within 'asn' is 'ASHEN'.
Can you help me to learn more?
(Other definitions for ashen that I've seen before include "'Very pale, from shock say (5)'" , "Unhealthily pale" , "showing signs of anaemia" , "White-faced" , "Pallid like fire residue" .)