Warning about British prince (6)
I believe the answer is:
albert
'prince' is the definition.
(I know that Albert is a prince consort)
'warning about british' is the wordplay.
'warning' becomes 'alert' (alert is a kind of warning).
'about' is an insertion indicator.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'alert' going around 'b' is 'ALBERT'.
(Other definitions for albert that I've seen before include "Queen Victoria's Prince Consort" , "and 7: French missionary" , "Old watch chain" , "London bridge, Memorial" , "M [MUSEUM] with 18 [VICTORIA]" .)