Like ring road section during test (7)
I believe the answer is:
orbital
'like ring road' is the definition.
(an orbital is a ring road)
'section during test' is the wordplay.
'section' becomes 'bit' (I've seen this in other clues).
'during' means one lot of letters goes inside another.
'test' becomes 'oral' (oral is a type of examination).
'bit' put into 'oral' is 'ORBITAL'.
(Other definitions for orbital that I've seen before include "Rob tail (anag.)" , "that's going around" , "Of road, circling a town" , "Descriptive of the M25" , "going round the city" .)