By way of the tube, getting to the bridge (7)
I believe the answer is:
viaduct
'the bridge' is the definition.
(viaduct is a kind of bridge)
'by way of the tube getting' is the wordplay.
'by way of' becomes 'via' (via means by way of or by means of).
'the tube' becomes 'duct' (type of tube or canal).
'getting' is a charade indicator (letters next to each other).
'via'+'duct'='VIADUCT'
'to' acts as a link.
(Other definitions for viaduct that I've seen before include "Bridge carrying a road over a river or valley" , "Bridge across a valley" , "Kind of road over a road" , "Rail bridge over valley" , "Long arched structure" .)