Hours trapped in tube and cars snarling up capital (9)
I believe the answer is:
bucharest
'capital' is the definition.
(capital of Romania)
'hours trapped in tube and cars snarling up' is the wordplay.
'hours' becomes 'h'.
'trapped in' is an insertion indicator.
'and' is a charade indicator (letters next to each other).
'snarling up' is an anagram indicator (I've seen 'snarled up' mean this (I've seen this in other clues)).
'tube' put after 'cars' is 'carstube'.
'carstube' anagrammed gives 'bucarest'.
'h' going within 'bucarest' is 'BUCHAREST'.
(Other definitions for bucharest that I've seen before include "European city" , "Capital of Romania" , "Balkan city" , "European capital" , "Romanian capital" .)