Meanwhile, after Bury the motorway is backed up (7)
I believe the answer is:
interim
'meanwhile' is the definition.
(thesaurus)
'after bury the motorway is backed up' is the wordplay.
'after' means one lot of letters go next to another.
'bury' becomes 'inter' ('inter' can be a synonym of 'bury').
'the motorway' becomes 'mi' (resembles M1, English motorway).
'is backed up' is a reversal indicator.
'mi' written backwards gives 'im'.
'inter'+'im' is 'INTERIM'.
(Other definitions for interim that I've seen before include "Meantime; temporary" , "Meantime - provisional" , "An intervening period of time" , "Meanwhile" , "temporary period" .)