Agree to write some letters (10)
I believe the answer is:
correspond
This might be a double definition.
'agree' is the first definition.
(I know that agree can be written as correspond)
'write some letters' is the second definition.
'correspond' can be an answer for 'write' (to correspond is to exchange letters with someone). I'm unsure of the 'some letters' bit.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for correspond that I've seen before include "Have similar functions" , "Have a close similarity" , "Swap letters" , "Keep in touch by letter" , "Communicate by letter" .)