In Italy, a mere 50% of road rage takes place, essentially, with learner reversing (4,5)

'in italy a mere' is the definition.
I know nothing about this answer so I can't judge whether this works.

'50% of road rage takes place essentially with learner reversing' is the wordplay.
'50% of' means to take half the letters.
'takes place essentially' becomes 'ka' (I can't explain this - if you can you should believe this answer much more).
'with' means one lot of letters go next to another.
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'reversing' shows that the letters should be reversed in order.
'road' with half the letters taken is 'ad'.
'ad'+'rage'+'ka'+'l'='adragekal'
'adragekal' in reverse letter order is 'LAKE GARDA'.

Can you help me to learn more?