The most common and most likely answer to this crossword clue is the 7 letter word CANVASS
I've seen this crossword clue in Independent
C
A
N
V
A
S
S
More clues leading to the result CANVASS
- Is able to vote as several standing initially seek support
- Broadcast medium on which one might draw for campaign
- Vans breaking down in shed curtailed campaign
- Drum up support for painting on Sunday
- May see fool seek support
- What politician may do with coarse material on son
- Sails south in attempt to raise political support
- Seek opinion from son on work of art
- Scrutinize painting by son
- What politician may need to do with drink besetting Nationalist societies?
Buddy explains!

The straight part
We know that "campaign" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case campaign = canvass.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.