Model virtue of a pet (9)
I believe the answer is:
favourite
'pet' is the definition.
(I know that pet can be written as favourite)
'model virtue of a' is the wordplay.
'model' is an anagram indicator (letters must be modelled into a new form ).
'virtue'+'of'+'a'='virtueofa'
'virtueofa' anagrammed gives 'FAVOURITE'.
(Other definitions for favourite that I've seen before include "royal confidant" , "that attracts lots of money" , "Specially dear person - likely winner" , "Preferred" , "leading contender" .)