Each street starts, ie one way and that’s the most straightforward (7)
I believe the answer is:
easiest
'most straightforward' is the definition.
Both the definition and answer are superlative adjectives. Maybe you can see a link between them that I don't see?
'each street starts ie one way and that's the' is the wordplay.
'each' becomes 'ea' (abbreviation).
'starts' suggests taking the first letters.
'one way' becomes 's' (Compass direction - South).
'and' is a charade indicator (letters next to each other).
'that's the' becomes 't' (the is pronounced as a 't' sound in some dialects).
The initial letter of 'street' is 's'.
'ea'+'s'+'ie'+'s'+'t'='EASIEST'
Can you help me to learn more?
(Other definitions for easiest that I've seen before include "Most simple" , "most like pie" , "Most effortless" , "Least difficult" , "Simplest" .)