Criminal? Chap leading soldiers suppressing truth (10)
I believe the answer is:
malefactor
'criminal?' is the definition.
(I know that criminal can be written as malefactor)
'chap leading soldiers suppressing truth' is the wordplay.
'chap' becomes 'male' (I've seen this in other clues).
'leading' is a charade indicator (letters next to each other).
'soldiers' becomes 'OR' (Other Ranks).
'suppressing' indicates putting letters inside.
'truth' becomes 'fact' (true facts).
'male'+'or'='maleor'
'maleor' enclosing 'fact' is 'MALEFACTOR'.
(Other definitions for malefactor that I've seen before include "Wrongdoer" , "Sinner" , "One doing wrong" , "bad person?" , "culprit?" .)