One with pride in Sir Tristram’s birthplace, we hear? (7)
I believe the answer is:
lioness
'one with pride' is the definition.
(as in a pride of lions)
'sir tristram's birthplace we hear?' is the wordplay.
'sir tristram's birthplace' becomes 'lyonnesse' (mythical country in Arthurian legend).
'we hear?' indicates a 'sounds like' (homophone) clue.
'lyonnesse' is a homophone of 'LIONESS'.
'in' acts as a link.
(Other definitions for lioness that I've seen before include "Female carnivore" , "Queen of beasts?" , "Elsa, for one" , "Wild animal" , "Big beast's mate" .)