Pet cuckoo is tame, welcoming return of experts (7,3)
I believe the answer is:
siamese cat
'pet' is the definition.
(type of cat)
'cuckoo is tame welcoming return of experts' is the wordplay.
'cuckoo' indicates an anagram (I've seen this in other clues).
'welcoming' is an insertion indicator (in sense of 'inviting in').
'return of' says the letters should be written backwards.
'experts' becomes 'aces' (ace is a kind of expert).
'aces' back-to-front is 'seca'.
'is'+'tame'='istame'
'istame' is an anagram of 'siamet'.
'siamet' placed around 'seca' is 'SIAMESE CAT'.
(Other definitions for siamese cat that I've seen before include "Animal" , "Carnivore" , "Feline breed" , "Domestic pet" , "What might be cunning" .)