Second course that was designed for the better (4-4)

I believe the answer is:

tick-tack

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

'was designed for the better' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'second course' is the wordplay.
'second' becomes 'tick' (both can mean a very short amount of time).
'course' becomes 'tack' (I've seen this before).
'tick'+'tack'='TICK-TACK'

'that' is the link.

Can you help me to learn more?

I've seen this clue in The Guardian.

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