Bury loose cash where motorways cross (11)
I believe the answer is:
interchange
'where motorways cross' is the definition.
(type of road junction)
'bury loose cash' is the wordplay.
'bury' becomes 'inter' (synonyms).
'loose cash' becomes 'change' (coins).
'inter'+'change'='INTERCHANGE'
(Other definitions for interchange that I've seen before include "station?" , "where roads meet" , "trade" , "Old truck" , "switch" .)