Crossing major road, eye problem is a frustration (6)
I believe the answer is:
stymie
'a frustration' is the definition.
(stymie can mean to frustrate or block a plan)
'crossing major road eye problem' is the wordplay.
'crossing' is an insertion indicator (to cross can mean to go over or around).
'major road' becomes 'mi' (resembles M1, English motorway).
'eye problem' becomes 'stye' (I've seen this before).
'mi' put into 'stye' is 'STYMIE'.
'is' acts as a link.
(Other definitions for stymie that I've seen before include "Obstruct as on putting green" , "'Hinder, prevent progress (6)'" , "Hinder, obstruct, thwart" , "Block or thwart, perhaps on putting green" , "Tricky situation" .)