The most common and most likely answer to this crossword clue is the 5 letter word SCRIM
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Buddy explains!

The straight part
We know that "E.g. curtain fabric" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case e.g. curtain fabric = scrim.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 SCRIM mean?
SCRIM noun- A kind of light cotton or linen fabric, often woven in openwork patterns, -- used for curtains, etc,.
- A large military scarf, usually camouflage coloured and used for concealment when not used as a scarf.
- A woven, nonwoven or knitted fabric composed of continuous strands of material used for reinforcing or strengthening membranes.
- A theater drop that appears opaque when a scene in front is lighted and transparent or translucent when a scene in back is lighted.
- A sheet of gauze etc. used to reduce the intensity of light.
- Thin canvas glued on the inside of panels to prevent shrinking, checking, etc.
- To use a scrim.
- A practice match between one or more organized teams usually in preparation for a more competitive format, such as a tournament.
- To participate in a scrim.