The most common and most likely answer to this crossword clue is the 5 letter word LOBBY
I've seen this crossword clue in The Guardian
L
O
B
B
Y
More clues leading to the result LOBBY
- Throw up near vestibule
- Look, baby, that’s not a pressure group!
- Look to leader from Brussels before campaign
- See baby without the presence of a pressure group
- Attempt to influence shy, loveless lad
- Campaign entry
- Solicit in entrance
- Lift next to waiting room
- Type of delivery adjacent to reception area
- Send up Times campaign?
Buddy explains!

The straight part
We know that "Campaign entry/Campaign/entry" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case campaign entry/campaign/entry = lobby.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does LOBBY mean?
LOBBY noun- An entryway or reception area; vestibule; passageway; corridor.
- That part of a hall of legislation not appropriated to the official use of the assembly.
- A class or group of people who try to influence public officials; collectively, lobbyists.
- A virtual area where players can chat and find opponents for a game.
- An apartment or passageway in the fore part of an old-fashioned cabin under the quarter-deck.
- A confined place for cattle, formed by hedges, trees, or other fencing, near the farmyard.
- A margin along either side of the playing field in the sport of kabaddi.
- To attempt to influence (a public official or decision-maker) in favor of a specific opinion or cause.
- Scouse (from lobscouse)