Worker I force to join a leftist group (6)

I believe the answer is:

antifa

I'm a little stuck... Click here to teach me more about this clue!

'leftist group' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'worker i force to join a' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'force' becomes 'f' (abbreviation in physics e.g. f=ma).
'to join' means one lot of letters go next to another.
'ant'+'i'+'f'+'a'='ANTIFA'

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

Want a hint initially instead of a full solution? Install my app