Get the soldier coming in to salute (5)
I believe the answer is:
greet
'to salute' is the definition.
(I've seen this in another clue)
'get the soldier coming in' is the wordplay.
'the soldier' becomes 're' (Royal Engineer).
'coming in' means one lot of letters goes inside another.
'get' placed around 're' is 'GREET'.
(Other definitions for greet that I've seen before include "Say hello, hail" , "Receive - salute" , "Address on arrival, say hello" , "Hail, salute" , "Give welcome to" .)