Pass on traffic warning and fix with utmost vigour (5,3,4)
I believe the answer is:
tooth and nail
'pass on traffic warning and fix with utmost vigour' is the definition.
I can't tell whether this definition defines the answer.
'and fix with utmost vigour' is the wordplay.
'fix' becomes 'nail' (I've seen this before).
'with' is a charade indicator (letters next to each other).
'utmost vigour' becomes 'tooth' (I can't justify this - if you can you should give a lot more credence to this answer).
'and'+'nail'='andnail'
'andnail' after 'tooth' is 'TOOTH-AND-NAIL'.
Can you help me to learn more?
(Other definitions for tooth and nail that I've seen before include "With greatest vigour" , "With the utmost vigour" , "With all possible vigour" , "Fiercely" , "(Fight) without restraint" .)