The most common and most likely answer to this crossword clue is the 8 letter word ESPOUSAL
I've seen this crossword clue in Independent
E
S
P
O
U
S
A
L
More clues leading to the result ESPOUSAL
- Adoption of English as a second language involving power over America
- Slippery slope limiting America's support
- Fall back, holding onto old American support for cause
- Backing unsettled Poles to take America to heart
- Support French art with chum touring old states
- Slippery slope, embracing America’s Act of Union?
- Assumption that when borders cease to exist, despot must fall
- Championing Poles travelling around America
- States accepted by Poles, perhaps, for adoption
- Suspect Poles will accept America getting support
Buddy explains!

The straight part
We know that "support for cause" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case support for cause = espousal.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 ESPOUSAL mean?
ESPOUSAL noun- A betrothal.
- A wedding ceremony.
- Adoption of a plan, cause, or idea.