British self-respect in a new plant (7)
I believe the answer is:
begonia
'plant' is the definition.
(begonia is a kind of plant)
'british self-respect in a new' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'self-respect' becomes 'ego' (ego can mean one's sense of self).
'new' indicates anagramming the letters.
'in'+'a'='ina'
'ina' with letters rearranged gives 'nia'.
'b'+'ego'+'nia'='BEGONIA'
(Other definitions for begonia that I've seen before include "colourful flower" , "Herbaceous plant whose flowers have no petals" , "Common garden plant" , "bloomer" , "Tropical plant" .)