Screw up when cutting motorway reservation (7)
I believe the answer is:
scruple
'reservation' is the definition.
(thesaurus)
'screw up when cutting motorway' is the wordplay.
I cannot really see how this works, but
'up' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for scruple that I've seen before include "Moral hesitation, small weight" , "Fine moral consideration" , "Moral uncertainty" , "A light-weight" , "carrying little weight" .)