Commend a very quiet tailless dog (7)
I believe the answer is:
approve
'commend' is the definition.
(thesaurus)
'a very quiet tailless dog' is the wordplay.
'very quiet' becomes 'pp'.
'tailless' means to remove the last letter.
'dog' becomes 'rover' (I've seen this before).
'rover' with its final letter taken off is 'rove'.
'a'+'pp'+'rove'='APPROVE'
(Other definitions for approve that I've seen before include "Say yes to" , "OK" , "Consider right" , "Officially endorse" , "Give the nod to, sanction" .)