Looking up to billboard on motorway loop (8)
I believe the answer is:
admiring
'looking up to' is the definition.
('admire' can be a synonym of 'look up to')
'billboard on motorway loop' is the wordplay.
'billboard on' becomes 'ad' (I can't explain this - if you can you should believe this answer much more).
'motorway' becomes 'MI' (resembles Ma, English motorway).
'loop' becomes 'ring' (I've seen this in another clue).
'ad'+'mi'+'ring'='ADMIRING'
Can you help me to learn more?
(Other definitions for admiring that I've seen before include "Having a high regard for" , "Regarding with respect or approval" , "Regarding highly" , "Looking up to" , "Approving" .)