Not a rosy future for a guard who's not alert (3,7)

'not a rosy future' is the definition.
I don't know anything about this answer so I can't tell whether this works.

'guard who's not alert' is the wordplay.
I cannot quite understand how this works, but
'guard' could be 'lookout' (lookout is a kind of guard) and 'lookout' is present in the answer.
The remaining letters 'bad' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

'for a' acts as a link.

Can you help me to learn more?