Present cardinal to army corps (4)
I believe the answer is:
here
'present' is the definition.
('here' can be similar in meaning to 'present')
'cardinal to army corps' is the wordplay.
'cardinal' becomes 'he' (I've seen this in other clues**).
'to army corps' becomes 're' (I've seen this in other clues).
'he'+'re'='HERE'
(Other definitions for here that I've seen before include "final clue?" , "The present location" , "In attendance" , "In this place - present" , "Hither" .)