Be situated in Beaulieu (3)
I believe the answer is:
lie
'be situated' is the definition.
(I've seen this in another clue)
'in beaulieu' is the wordplay.
'in' indicates the answer is hidden within the clue.
'LIE' can be found hidden inside 'beaulieu'.
(Other definitions for lie that I've seen before include "Whopper" , "Fib in alienation" , "Porky" , "Pork pie" , "Commit perjury" .)