Start filling Aussie's truck, carrying melons to the north (9)
I believe the answer is:
institute
'start' is the definition.
(I've seen this before)
'filling aussie's truck carrying melons to the north' is the wordplay.
'filling aussie' becomes 'in' (I can't justify this - if you can you should give a lot more credence to this answer).
'truck' becomes 'ute' (Australian abbreviation for utility vehicle).
'carrying' is a charade indicator (letters next to each other) (in a down clue, the bottom letters carry others).
'melons' becomes 'tits' (I've seen this in another clue).
'to the north' is a reversal indicator (in a down clue, letters go up or 'northward').
'tits' backwards is 'stit'.
'ute' put after 'stit' is 'stitute'.
'in'+'stitute'='INSTITUTE'
Can you help me to learn more?
(Other definitions for institute that I've seen before include "Organisation for promotion of scientific or educational activity" , "Scientific, educational or social organisation" , "order as before" , "Begin (legal proceedings)" , "Establish, educational organisation" .)