See a piece of timber to block the way (4)
I believe the answer is:
clog
'block the way' is the definition.
'clog' can be an answer for 'block' (clogging is a kind of blocking). I am not certain of the 'the way' bit.
'see a piece of timber' is the wordplay.
'see' becomes 'c' (the word for the letter, according to Chambers).
'a piece of timber' becomes 'log' (I am not sure about this - if you are sure you should believe this answer much more).
'c'+'log'='CLOG'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for clog that I've seen before include "Become blocked with wooden-soled shoe" , "Jam" , "Block; sabot" , "Footwear - hamper" , "Obstruct the wooden shoe" .)