The most common and most likely answer to this crossword clue is the 5 letter word BELOW
I've seen this crossword clue in Financial Times
B
E
L
O
W
More clues leading to the result BELOW
- Nobel author removing one line further on in the text
- Half-hearted shout, not on deck
- Energy limited by assault further down
- Live down under
- Cry “LibDem’s leader’s gone down!”
- Life’s ending in calamity, where the damned end?
- Half-hearted shout in the basement?
- Not above cutting grass with ecstasy
- Subordinate to roar half-heartedly
- Energy-fuelled blast in Hell
Buddy explains!

The straight part
We know that "basement" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case basement = below.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 BELOW mean?
BELOW adverb- In a lower place.
- On a lower storey.
- Further down.
- On a lower deck.
- (of a temperature) Below zero.
- Lower in spatial position than.
- Within the writing of a given document which follows a particular appearance of the word "below".
- Lower in value, price, rank or concentration than.
- Downstream of.
- South of.
- Unsuitable to the rank or dignity of; beneath.
- (stage directions) Downstage of.