The most common and most likely answer to this crossword clue is the 7 letter word SUDSIER
S
U
D
S
I
E
R
More clues leading to the result SUDSIER
Buddy explains!
The straight part
We know that "increasingly in a lather" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case increasingly in a lather = sudsier.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.