Commanding officer right get soldier a dog (5)
I believe the answer is:
corgi
'a dog' is the definition.
(corgi is a kind of dog)
'commanding officer right get soldier' is the wordplay.
'commanding officer' becomes 'co'.
'right' becomes 'r' (common abbreviation).
'get' means one lot of letters go next to another.
'soldier' becomes 'gi' (government issue or general issue).
'co'+'r'+'gi'='CORGI'
(Other definitions for corgi that I've seen before include "Toy car manufacturer" , "Welsh breed of short-legged dog" , "The Queen's favourite?" , "Cardigan or Pembroke dog" , "Royal canine" .)