Ancestor in troop movement to Hu?, for the most part going to 'Nam, slipped up (10)

'ancestor in troop movement' is the definition.
The definition suggests a singular noun which matches the answer.

'hu? for the most part going to 'nam slipped up' is the wordplay.
'for' means one lot of letters go next to another (I've seen this in other clues).
'the most part going' becomes 'proto' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'slipped up' says the letters should be written in reverse (I've seen 'slipping up' mean this (in a down clue, letters go up)).
'nam' back-to-front is 'man'.
'hu' put after 'proto' is 'protohu'.
'protohu'+'man'='PROTOHUMAN'

'to' acts as a link.

Can you help me to learn more?