Make fun of city MP with nothing on (7)
I believe the answer is:
lampoon
'make fun of' is the definition.
(lampooning is a kind of making fun of)
'city mp with nothing on' is the wordplay.
'city' becomes 'LA' (Los Angeles).
'with' says to put letters next to each other.
'nothing' becomes 'O' (looks like zero - 0).
'la'+'mp'+'o'+'on'='LAMPOON'
(Other definitions for lampoon that I've seen before include "Satirise, ridicule" , "Mock" , "send-up" , "Written ridicule of polo man" , "Literary satire" .)