Approving zebras sent in giant parcel (9)

I believe the answer is:

assenting

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

'approving' is the definition.
(thesaurus)

'zebras sent in giant parcel' is the wordplay.
'ASSENTING' is hidden within the letters.
However, I am uncertain how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for assenting that I've seen before include "Saying yes" , "Agreeing" .)

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

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