Move framework of bars supporting motorway (7)
I believe the answer is:
migrate
'move' is the definition.
(migrating is a kind of moving)
'framework of bars supporting motorway' is the wordplay.
'framework of bars' becomes 'grate'.
'supporting' means one lot of letters go next to another (in a down clue, some letters go below others).
'motorway' becomes 'mi' (resembles M1, English motorway).
'grate' put after 'mi' is 'MIGRATE'.
(Other definitions for migrate that I've seen before include "Move from one country to another to settle" , "Change habitat (seasonally, perhaps)" , "Ragtime (anag)" , "Move to a new area" , "Move with the seasons" .)