Command to get over across the road (5)
I believe the answer is:
order
'command' is the definition.
(order is a kind of command)
'over across the road' is the wordplay.
'over' becomes 'oer' ('o'er' can be a synonym of 'over'**).
'across' is an insertion indicator.
'the road' becomes 'rd' (abbreviation).
'oer' placed around 'rd' is 'ORDER'.
'to get' acts as a link.
(Other definitions for order that I've seen before include "booking" , "Direct or requisition" , "Apply for - class" , "Group living under a religious rule" , "Direct - sequence" .)