Jolly English opener on top of other side (4,2)

I believe the answer is:

ever so

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

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

'english opener on top of other side' is the wordplay.
'opener' suggests taking the first letters.
'on top of' says to put letters next to each other.
'other side' becomes 'verso' (verso is a kind of side. I am not sure about the 'other' bit.).
The first letter of 'english' is 'e'.
'e'+'verso'='EVER SO'

Can you help me to learn more?

(Other definitions for ever so that I've seen before include "Very much" , "Jolly" , "Greatly" , "To a very great extent" , "really" .)

I've seen this clue in The Independent.

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