Hound men in action partly retreating (6)
I believe the answer is:
canine
'hound' is the definition.
(thesaurus)
'men in action partly retreating' is the wordplay.
'partly' says the answer is hidden in the clue.
'retreating' says the letters should be written in reverse.
'eninac' is hidden in the letters of 'men in action'.
'eninac' written backwards gives 'CANINE'.
(Other definitions for canine that I've seen before include "Relating to dogs" , "Maybe setter" , "Tooth; dog" , "Fang" , "Doggy; tooth" .)