Friendly stroll, skirting northbound main road (7)
I believe the answer is:
amiable
'friendly' is the definition.
(similar in meaning)
'stroll skirting northbound main road' is the wordplay.
'stroll' becomes 'amble' (synonyms).
'skirting' indicates putting letters inside.
'northbound' is a reversal indicator.
'main road' becomes 'AI' (resembles A1, major UK road).
'ai' back-to-front is 'ia'.
'amble' placed around 'ia' is 'AMIABLE'.
(Other definitions for amiable that I've seen before include "Friendly, kindly" , "'Friendly, pleasant and good-tempered (7)'" , "'Cordial, friendly (7)'" , "Of sweet and friendly disposition" , "Good-humoured" .)