Rescue dog with no tail (8)
I believe the answer is:
retrieve
'rescue' is the definition.
(I've seen this before)
'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 removed is 'RETRIEVE'.
(Other definitions for retrieve that I've seen before include "Get back (lost item)" , "Find and bring back" , "Regain or fetch" , "(Of dog) fetch shot game" , "Recover" .)