Soldier's first and last post (4)
I believe the answer is:
send
'post' is the definition.
(I know that post can be written as send)
'soldier's first and last' is the wordplay.
'soldier's first' becomes 's' (1st letter of 'soldier').
'and' says to put letters next to each other.
'last' becomes 'end' (I've seen this in another clue).
's'+'end'='SEND'
(Other definitions for send that I've seen before include "Sentence to a prison term" , "Dispatch by post" , "Transmit (message)" , "and 2: Advise" , "Cause to go for" .)