Turn up at long last with a dog (3)
I believe the answer is:
pug
'a dog' is the definition.
(pug is a kind of dog)
'turn up at long last' is the wordplay.
'turn' shows that the letters should be reversed in order.
'at' says to put letters next to each other.
'last' indicates one should take the final letters.
The final letter of 'long' is 'g'.
'up' backwards is 'pu'.
'pu'+'g'='PUG'
'with' is the link.
(Other definitions for pug that I've seen before include "A dog; pack with clay" , "Small boxer" , "Flat-nosed dog breed" , "Dog with broad flat nose, or an informal boxer" , "Small dog with flat nose and wrinkled face" .)