Imposing bear to be ostentatious (10)
I believe the answer is:
grandstand
'imposing bear to be ostentatious' is the definition.
I can't judge whether this definition defines the answer.
'bear to be ostentatious' is the wordplay.
'bear' becomes 'stand' (bear can mean to stand or endure).
'to' says to put letters next to each other (I've seen this in other clues).
'be ostentatious' becomes 'grand'.
'stand' put after 'grand' is 'GRANDSTAND'.
Can you help me to learn more?
(Other definitions for grandstand that I've seen before include "Play to the audience" , "Main structure for watching sporting events" , "Racecourse construction" , "From which spectators watch" , "Main area for race spectators" .)