He has no address book after heading to virtual city (7)
I believe the answer is:
vagrant
'he has no address' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'book after heading to virtual city' is the wordplay.
'book' becomes 'nt' (I've seen this in other clues).
'after' means one lot of letters go next to another.
'heading to' says to take the initial letters.
'city' becomes 'agra' (Indian city).
The first letter of 'virtual' is 'v'.
'v'+'agra'='vagra'
'nt' after 'vagra' is 'VAGRANT'.
Can you help me to learn more?
(Other definitions for vagrant that I've seen before include "Person of no fixed abode" , "Unsettled person, a tramp" , "Traveller" , "Homeless person" , "Itinerant" .)