Dog with no tail - get back! (8)
I believe the answer is:
retrieve
'get back' is the definition.
(thesaurus)
'dog with no tail' is the wordplay.
'dog' becomes 'retriever' (retriever is a kind of dog).
'with no tail' means to remove the last letter.
'retriever' with its last letter taken away is 'RETRIEVE'.
(Other definitions for retrieve that I've seen before include "Get or bring back something" , "Get back (lost item)" , "Go for and bring back" , "Win back" , "Revere it to get back" .)