Engine check for Army say (7)
I believe the answer is:
service
'army say' is the definition.
(army is a kind of service)
'engine check' is the wordplay.
I cannot really see how this works, but
'engine' could be 'ice' (I've seen this before) and 'ice' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
'for' is the link.
Can you help me to learn more?
(Other definitions for service that I've seen before include "Set of dishes" , "Periodic car maintenance" , "Tennis opening shot" , "Armed force - assistance" , "funeral, say" .)