It upsets English honour by writing to The Board (6)
I believe the answer is:
timber
'board' is the definition.
(I've seen this before)
'it upsets english honour by writing to' is the wordplay.
I cannot quite understand how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found within the answer.
'english' could be 'e' (abbreviation) and 'e' is located in the answer.
'honour' could be 'mb' (MB is an example) and 'mb' is found in the answer.
'writing' could be 'r' (one of the traditional three R's of education) and 'r' is located in the answer.
A single letter 'i' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
'the' is the link.
Can you help me to learn more?
(Other definitions for timber that I've seen before include "Ash perhaps" , "Sawn wood" , "Watch out for falling tree!" , "The tree's falling!" , "Warning cry that a tree is about to fall" .)