Are current lines and numbers entered first? (4,4)
I believe the answer is:
area code
'numbers entered first?' is the definition.
(an area code is at the beginning of a phone number)
'are current lines' is the wordplay.
'current' becomes 'ac' (alternating current).
'lines' becomes 'ode' (I've seen this before).
'are'+'ac'+'ode'='AREA CODE'
'and' is the link.
(Other definitions for area code that I've seen before include "Some phone numbers" , "Telephone prefix assigned to a region" , "Regional dialling no." , "Location-specific numbers" , "Dialling sequence for, eg, a town" .)