Masterly advert for a new pet (5)

I believe the answer is:

adept

'masterly' is the definition.
(thesaurus)

'advert for a new pet' is the wordplay.
'advert' becomes 'ad' (synonyms).
'for' says to put letters next to each other.
'a new' is an anagram indicator.
'pet' with letters rearranged gives 'ept'.
'ad'+'ept'='ADEPT'

(Other definitions for adept that I've seen before include "Handy" , "efficient" , "Skilful and adroit" , "Highly proficient" , "skilled performer" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app