The most common and most likely answer to this crossword clue is the 4 letter word ELLS
I've seen this crossword clue in The Daily Telegraph
E
L
L
S
More clues leading to the result ELLS
Buddy explains!

The straight part
We know that "Lengths of cloth" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case lengths of cloth = ells.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 ELLS mean?
ELLS noun- A measure for cloth. An English ell was 1 1/4 yards (45 inches), whereas a Scottish ell measured only about 37 inches and a Flemish ell was 3/4 yard (27 inches).
- The name of the Latin-script letter L.
- An extension usually at right angles to one end of a building.
- Something that is L-shaped.