A male engineer is present (4)
I believe the answer is:
here
'is present' is the definition.
(both can mean in attendance)
'a male engineer' is the wordplay.
'a male' becomes 'he' (he refers to a man).
'engineer' becomes 're' (Royal Engineer).
'he'+'re'='HERE'
(Other definitions for here that I've seen before include "The present location" , "In this place - present" , ""___ be dragons" (old map inscription?)" , "Present; I say!" , "To hand" .)