A model unexpectedly receiving right noble rank (7)
I believe the answer is:
earldom
'noble rank' is the definition.
(I've seen this before)
'a model unexpectedly receiving right' is the wordplay.
'unexpectedly' is an anagram indicator.
'receiving' indicates putting letters inside.
'right' becomes 'r' (common abbreviation).
'a'+'model'='amodel'
'amodel' is an anagram of 'ealdom'.
'ealdom' enclosing 'r' is 'EARLDOM'.
(Other definitions for earldom that I've seen before include "Nobleman's estate" , "What sort of noble has" , "A noble's lands or title" , "Lands of a nobleman" , "noble area of country" .)