Old canine trained, beginning to talk? (7)
I believe the answer is:
ancient
'old' is the definition.
(similar in meaning)
'canine trained beginning to talk?' is the wordplay.
'trained' indicates an anagram (to train can mean to grow something into a shape).
'beginning to' suggests taking the first letters.
The initial letter of 'talk' is 't'.
'canine' with letters rearranged gives 'ancien'.
'ancien'+'t'='ANCIENT'
(Other definitions for ancient that I've seen before include "from olden times" , "From the distant past" , "Old man" , "showing signs of wear?" , "so old-fashioned" .)