Unlikely Oscar for ‘Killers Working Together (5)

I believe the answer is:

orcas

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

''killers working together' is the definition.
I can't judge whether this defines the answer.

'unlikely oscar' is the wordplay.
'unlikely' indicates anagramming the letters (an unlikely spelling of the letters).
'oscar' with letters rearranged gives 'ORCAS'.

'for' acts as a link.

Can you help me to learn more?

(Other definitions for orcas that I've seen before include "Killers" , "Killer whales" .)

I've seen this clue in The Guardian.

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