Brand of large tent not quite finished (6)
I believe the answer is:
marque
'brand' is the definition.
(I know that brand can be written as marque)
'large tent not quite finished' is the wordplay.
'large tent' becomes 'marquee' (I've seen this before).
'not quite finished' means to remove the last letter (most but not all of the word).
'marquee' with its last letter taken away is 'MARQUE'.
'of' is the link.
(Other definitions for marque that I've seen before include "Brand name" , "Make of car" , "Brand of car" , "Make most of large tent" , "Badge" .)