Friend to arrive shortly with army chaplain (8)
I believe the answer is:
compadre
'friend' is the definition.
(I've seen this before)
'arrive shortly with army chaplain' is the wordplay.
'arrive' becomes 'come' (coming is a kind of arriving).
'shortly' means to remove the last letter.
'with' says to put letters next to each other.
'army chaplain' becomes 'padre' (I've seen this before).
'come' with its final letter removed is 'com'.
'com'+'padre'='COMPADRE'
'to' acts as a link.
(Other definitions for compadre that I've seen before include "American friend" , "Friend, companion" , "Friend (from Spanish)" .)