Gannet leapt out in house (11)
I believe the answer is:
plantagenet
'house' is the definition.
(historical royal house)
'gannet leapt out' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'gannet'+'leapt'='gannetleapt'
'gannetleapt' anagrammed gives 'PLANTAGENET'.
'in' acts as a link.
(Other definitions for plantagenet that I've seen before include "Member of English royal house from Henry II to Richard III" , "9 [HOUSE]" , "Former English royal family" , "royal dynasty" .)