Lawgiver playing part in generalissimo’s escape (5)
I believe the answer is:
moses
'lawgiver' is the definition.
(Moses handed down the Ten Commandments)
'playing part in generalissimo's escape' is the wordplay.
'playing part in' indicates the answer is hidden within the clue.
'MOSES' is hidden in the letters of 'generalissimos escape'.
(Other definitions for moses that I've seen before include "Hebrew prophet and lawgiver" , "Hebrew prophet who received the ten commandments" , "He led the Jews from captivity in Egypt" , "Biblical prophet" , "He led the Jews from bondage in Egypt" .)