Fine linen in two-thirds of university clubs (7)
I believe the answer is:
cambric
'fine linen' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for cambric that I've seen before include "Thin linen or cotton cloth" , "Fine white linen" , "light cloth" , "Material" , "Lightweight cotton or linen cloth" .)