The most common and most likely answer to this crossword clue is the 4 plus 4 plus 2 plus 5 letter word COME RAIN OR SHINE
I've seen this crossword clue in Independent
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More clues leading to the result COME RAIN OR SHINE
- One choir remains in disarray whatever happens
- Fractured no more, I care to protect bone, whatever happens
- Supply son with heroin? A crime, whatever the circumstances
- Regardless of circumstances in romance, hero is prepared
- Racehorse I’m on in training, whatever the weather
- Going ahead without precipitate assessment?
- What can give mariner cohesion under any conditions
- Hero in is Cameron, struggling no matter what?
- Racehorse I'm on in training, whatever the weather
- I’m on racehorse, in winds, whatever the weather?
Buddy explains!

The straight part
We know that "Going ahead without precipitate assessment?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case going ahead without precipitate assessment? = come rain or shine.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.