Wife devoured judge in bottom section of course (5,4)
I believe the answer is:
water jump
'section of course' is the definition.
(obstacle in a horse race)
'wife devoured judge in bottom' is the wordplay.
'wife' becomes 'w'.
'devoured' becomes 'ate' (I've seen this in other clues).
'judge' becomes 'j' (abbreviation for judge).
'in' means one lot of letters goes inside another.
'bottom' becomes 'rump' (synonyms).
'j' put inside 'rump' is 'rjump'.
'w'+'ate'+'rjump'='WATER JUMP'
(Other definitions for water jump that I've seen before include "Horse race obstacle" , "Steeplechase feature" , "Steeplechase obstacle" .)