Labourer’s van heading north, visibly empty (5)
I believe the answer is:
navvy
'labourer's' is the definition.
(navvy is a kind of labourer)
'van heading north visibly empty' is the wordplay.
'heading north' is a reversal indicator.
'empty' means to remove the middle letters.
'visibly' with its middle taken out is 'vy'.
'van' back-to-front is 'nav'.
'nav'+'vy'='NAVVY'
(Other definitions for navvy that I've seen before include "Labourer working on canals, roads, railways etc?" , "Labourer, originally digging the canals" , "Construction worker" , "Canal labourer" , "Construction labourer" .)