The most common and most likely answer to this crossword clue is the 8 letter word THATCHER
I've seen this crossword clue in Financial Times
T
H
A
T
C
H
E
R
More clues leading to the result THATCHER
- Building's top plant installer?
- Not this dear French stateswoman
- Time one devises a plot to snare politician
- PM once rocked the chart
- Former number one in the chart following remix
- Yon Conservative, the female PM once
- Politician, Tory leader and mother hen, perhaps?
- Old blue tit losing it with one on an egg?
- May’s predecessor, the well-known revolutionary meeting resistance
- That Conservative woman
Buddy explains!
The straight part
We know that "Former number one" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case former number one = thatcher.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.