The most common and most likely answer to this crossword clue is the 6 letter word BALEEN
I've seen this crossword clue in Financial Times
B
A
L
E
E
N
More clues leading to the result BALEEN
Buddy explains!
The straight part
We know that "In the past it’s been squeezing a lady’s top" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in the past it’s been squeezing a lady’s top = baleen.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 BALEEN mean?
BALEEN noun- The bony material that makes up the plates in the mouth of the baleen whale, Mysticeti, which it uses to trap its food; formerly used in corsetry
- A baleen whale