The most common and most likely answer to this crossword clue is the 6 letter word IMPEND
I've seen this crossword clue in Financial Times
I
M
P
E
N
D
More clues leading to the result IMPEND
- Threaten devil will take the hindmost
- Loom I repair without pressure
- Threaten small creature with extinction?
- Current tip of warp is fed in to fix loom
- Threaten one member’s demise
- Threaten to pin tail on monkey
- Threaten
- Threaten current elected politician on purpose
- This compiler’s reportedly composed approach
- Threaten mischievous child with death
Buddy explains!

The straight part
We know that "loom" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case loom = impend.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 IMPEND mean?
IMPEND verb- To hang or be suspended over (something); to overhang.
- Figuratively to hang over (someone) as a threat or danger.
- To threaten to happen; to be about to happen, to be imminent.
- To pay.