Crossword Genius

Going off then to pack a kind of vase (2,3,4)

Ross

I believe the answer is:

on the turn

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

'going off' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for on the turn that I've seen before include "change" , "Going sour" .)

I've seen this clue in the Evening Standard.
Want a hint initially instead of a full solution? Install my app