Didn't overlook anything, as to not lose Focus on back road (12)

I believe the answer is:

concentrated

I'm a little stuck... Click here to teach me more about this clue!

'didn't overlook anything as to not lose' is the definition.
I can't judge whether this definition defines the answer.

'focus on back road' is the wordplay.
'focus' becomes 'concentrate' (synonyms).
'on back road' becomes 'd' (I can't explain this - if you can you should believe this answer much more).
'concentrate'+'d'='CONCENTRATED'

Can you help me to learn more?

(Another definition for concentrated that I've seen is " Focused - made denser".)

I've seen this clue in The Irish Times.

Want a hint initially instead of a full solution? Install my app