Surprised comment on US soldier's pet (5)
I believe the answer is:
corgi
'pet' is the definition.
(I know that corgi is a type of Dog)
'surprised comment on us soldier's' is the wordplay.
'surprised comment on' becomes 'cor' (I am not sure about this - if you are sure you should believe this answer much more).
'us soldier' becomes 'GI' (informal term for a US soldier).
'cor'+'gi'='CORGI'
Can you help me to learn more?
(Other definitions for corgi that I've seen before include "pet in 9 [CARDIFF]?" , "Royal canine" , "Dog popular with British royals" , "Toy car manufacturer" , "Welsh breen of dog" .)