Wicked deeds by Zulu warriors over European links (9)

I believe the answer is:

impieties

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

'wicked deeds' is the definition.
Although both the answer and definition are plural nouns, I don't see how one could define the other.

'zulu warriors over european links' is the wordplay.
'zulu warriors' becomes 'impi' (I've seen this before).
'over' says to put letters next to each other.
'european' becomes 'E' (abbreviation e.g. EU).
'links' becomes 'ties' (tie can mean a connection or link).
'impi'+'e'+'ties'='IMPIETIES'

'by' is the link.

Can you help me to learn more?

I've seen this clue in The Times.

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