Tank's broken down more gates (9)
I believe the answer is:
gasometer
'tank's' is the definition.
(gasometer is a kind of tank)
'broken down more gates' is the wordplay.
'broken down' indicates anagramming the letters.
'more'+'gates'='moregates'
'moregates' with letters rearranged gives 'GASOMETER'.
(Other definitions for gasometer that I've seen before include "could be seen by the Oval" , "Game store (anag) - fuel store" , "source of fuel" , "Fuel storage tank" , "Large fuel tank" .)