Alert, as you'd expect the Marines to be? (5)
I believe the answer is:
alarm
'alert' is the definition.
(I know that alert can be written as alarm)
'as you'd expect the marines to be?' is the wordplay.
I cannot quite understand how this works, but
'as' could be 'ala' (French 'a la' - 'in the style of') and 'ala' is found in the answer.
'marines' could be 'rm' (abbreviation for 'Royal Marines') and 'rm' is present in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for alarm that I've seen before include "Strike fear" , "Noise that wakes" , "Device to signal danger" , "Frighten, disturb" , "Panicky arousal" .)