Steer north through curvy region with big curves (5)
I believe the answer is:
buxom
'region with big curves' is the definition.
I can't judge whether this defines the answer.
'steer north through curvy' is the wordplay.
'steer' becomes 'ox' (a steer is a castrated ox).
'north' shows that the letters should be reversed in order (in a down clue, letters go up or 'northward').
'through' is an insertion indicator (inserted letters go through the word).
'curvy' becomes 'bum' (I am not sure about this - if you are sure you should believe this answer much more).
'ox' written backwards gives 'xo'.
'xo' going into 'bum' is 'BUXOM'.
Can you help me to learn more?
(Other definitions for buxom that I've seen before include "Pleasingly plump" , "Chesty" , "Full-bosomed" , "Plump and attractive" , "Plump and comely" .)