Male engineers present (4)
I believe the answer is:
here
'present' is the definition.
('here' can be similar in meaning to 'present')
'male engineers' is the wordplay.
'male' becomes 'he'.
'engineers' becomes 're' (Royal Engineers).
'he'+'re'='HERE'
(Other definitions for here that I've seen before include "Present; I say!" , "At this stage" , "final clue?" , "In attendance" , "Present - at this point" .)