Commanding officer conceals dog (5)
I believe the answer is:
dingo
'dog' is the definition.
(dingoes are wild dogs)
'commanding officer conceals' is the wordplay.
'conceals' indicates a hidden word.
'DINGO' is hidden in the letters of 'commanding officer'.
(Other definitions for dingo that I've seen before include "Yellow Australian dog" , "Want a dog" , "dog running wild" , "One running wild in Australia" , "Aussie wild dog" .)