Distant station letters to be sent? (7)
I believe the answer is:
outpost
'distant station' is the definition.
(I've seen this before)
'letters to be sent?' is the wordplay.
'letters' becomes 'post' (letters in the mail or post).
'to' says to put letters next to each other (I've seen this in other clues).
'be sent?' becomes 'out' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'post' put after 'out' is 'OUTPOST'.
Can you help me to learn more?
(Other definitions for outpost that I've seen before include "A distant branch or settlement" , "Remote military site" , "distant location" , "Distant part (of empire)" , "Distant station or branch" .)