Boris Johnson captivates everyone with a couple of lines somewhere in London (4,4)
I believe the answer is:
pall mall
'somewhere in london' is the definition.
(street in Westminster)
'boris johnson captivates everyone with a couple of lines' is the wordplay.
'boris johnson' becomes 'PM' (prime minister Boris Johnson).
'captivates' is an insertion indicator.
'everyone' becomes 'all' (all people).
'with' is a charade indicator (letters next to each other).
'a couple of lines' becomes 'all' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'pm' placed around 'all' is 'pallm'.
'pallm'+'all'='PALL-MALL'
Can you help me to learn more?
(Other definitions for pall mall that I've seen before include "Game once played" , "Monopoly board includes this" , "Sixteenth and seventeenth century ball game" , "thoroughfare" , "London street (worth PS140 in 14)" .)