Fabric Queen twice displayed in legal action (8)
I believe the answer is:
cashmere
'fabric' is the definition.
(cashmere is a kind of fabric)
'queen twice displayed in legal action' is the wordplay.
'queen twice' can mean two substitutions for 'queen'.
'queen' becomes 'hm' (short for Her Majesty).
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'displayed in' means one lot of letters goes inside another.
'legal action' becomes 'case' (synonyms).
'hm'+'er'='hmer'
'hmer' put into 'case' is 'CASHMERE'.
(Other definitions for cashmere that I've seen before include "High-quality wool" , "Fabric from fine goat's wool" , "Fine soft wool for marchese" , "Expensive wool? Search me" , "Soft fabric made from goats' hair" .)