Army officer departs in cut (5)
I believe the answer is:
padre
'army officer' is the definition.
(military chaplain)
'departs in cut' is the wordplay.
'departs' becomes 'd' (common abbreviation e.g. train timetables).
'in' means one lot of letters goes inside another.
'cut' becomes 'pare' (paring is a kind of cutting).
'd' put inside 'pare' is 'PADRE'.
(Other definitions for padre that I've seen before include "Priest, chaplain" , "Chaplain to armed forces" , "Army serviceman?" , "Military chaplain" , "Sky pilot (military slang)" .)