Be in step in fortress when confronting the enemy (4,4)
I believe the answer is:
keep time
'confronting the enemy' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'be in step in fortress when' is the wordplay.
'be in step' becomes 'tim' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'fortress' becomes 'keep' (I've seen this before).
'when' becomes 'e' (I've seen this in other clues).
'keep'+'e'='keepe'
'tim' going within 'keepe' is 'KEEP TIME'.
Can you help me to learn more?
(Other definitions for keep time that I've seen before include "Observe rhythm accurately" , "as rhythm section in jazz band must do" .)