Write letters for a while (5)
I believe the answer is:
spell
This might be a double definition.
'write letters' is the first definition.
'spell' can be an answer for 'write' ('spell' can be a synonym of 'write'). I am not certain of the 'letters' bit.
'a while' is the second definition.
(I've seen this before)
'for' is the link.
Can you help me to learn more?
(Other definitions for spell that I've seen before include "Charm; short period" , "get letters in order" , "Incantation; splinter of wood" , "influence" , "something to cast" .)