A criticism coming up for soldier (4)
I believe the answer is:
para
'for soldier' is the definition.
(paratrooper)
'a criticism coming up' is the wordplay.
'criticism' becomes 'rap' (as in taking the rap for a mistake).
'coming up' says the letters should be written backwards (in a down clue, letters go up).
'a'+'rap'='arap'
'arap' back-to-front is 'PARA'.
(Other definitions for para that I've seen before include "Soldier (shortened)" , "Air-drop soldier" , "Brazilian state" , "Soldier that jumps from planes" , "High-jumper" .)