A load-bearing vehicle on a southern shelf (6)
I believe the answer is:
sledge
'a load-bearing vehicle' is the definition.
'sledge' can be an answer for 'vehicle' (sledge is a kind of vehicle). I'm unsure of the 'a load-bearing' bit.
'on a southern shelf' is the wordplay.
'on' means one lot of letters go next to another.
'a southern' becomes 's' (abbreviation).
'shelf' becomes 'ledge' (synonyms).
's' put next to 'ledge' is 'SLEDGE'.
Can you help me to learn more?
(Other definitions for sledge that I've seen before include "Vehicle on runners, for snow and ice" , "Narrow cart with runners for travelling on snow" , "Vehicle for transportation over snow" , "Vehicle mounted on runners" , "Put cricketer off" .)