Crossword Genius

Vines from expansive summit on the mountain, for example (4)

Ross

I believe the answer is:

apex

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

This could be a double definition.

'vines from expansive summit' is the first definition.
'apex' can be an answer for 'summit' (thesaurus). I'm unsure of the 'vines from expansive' bit.

'the mountain for example' is the second definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.

'on' acts as a link.

Can you help me to learn more?

(Other definitions for apex that I've seen before include "The tip or highest point (4)" , "The highest point or pointed end" , "Tip -- top" , "high-point" , "Cheap fare" .)

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