Looking up to notice on motorway telephone (8)
I believe the answer is:
admiring
'looking up to' is the definition.
('admire' can be a synonym of 'look up to')
'notice on motorway telephone' is the wordplay.
'notice' becomes 'ad' (both can mean an advertisement).
'on' means one lot of letters go next to another.
'motorway' becomes 'MI' (resembles M1, English motorway).
'telephone' becomes 'ring' (synonyms).
'ad'+'mi'+'ring'='ADMIRING'
(Other definitions for admiring that I've seen before include "Regarding highly" , "Approving" , "Having a high regard for" , "Looking up to" , "Appreciating" .)