Business trust ends on a thread (6)
I believe the answer is:
cotton
'a thread' is the definition.
(cotton is a kind of thread)
'business trust ends on' is the wordplay.
'business' becomes 'co'.
'ends' says to hollow out the word (remove centre letters).
'trust' with its middle taken out is 'tt'.
'co'+'tt'+'on'='COTTON'
(Other definitions for cotton that I've seen before include "Creamy-white natural fibre" , "Material" , "Source of cloth" , "Soft fabric and fluffy wool (6" , "Old golfer" .)