Clear front of Tyne Tunnel -- car's broken down (11)
I believe the answer is:
translucent
'clear' is the definition.
('translucent' can be similar in meaning to 'clear')
'front of tyne tunnel car's broken down' is the wordplay.
'front of' says to take the initial letters.
'broken down' indicates an anagram.
The first letter of 'tyne' is 't'.
'tunnel'+'cars'='tunnelcars'
'tunnelcars' is an anagram of 'ranslucent'.
't'+'ranslucent'='TRANSLUCENT'
(Other definitions for translucent that I've seen before include "Shining through" , "clear" , "See-through" , "Semi-transparent" , "Liquid shooter" .)