Ken, to Barbie
'ken to barbie' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for beau that I've seen before include "An old boy friend like Brummel?" , "An old dandy like Brummel" , "Dandy - attentive companion" , "French boyfriend" , "Dandy - lover" .)
(Other definitions for boyfriend that I've seen before include "other half?" , "Close relationship with him" , "subject of musical" , "Close associate" , "woman may hope to become union member" .)