Stephen, a crusader, holds up defeat (4)
I believe the answer is:
cane
'defeat' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'stephen a crusader holds up' is the wordplay.
'holds' indicates the answer is hidden within the clue.
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'enac' can be found hidden inside 'stephen a crusader'.
'enac' in reverse letter order is 'CANE'.
Can you help me to learn more?
(Other definitions for cane that I've seen before include "Slender support, for 32 across say" , "e.g. Bamboo stem" , "Hollow stem of wood" , "Hollow jointed stem of, say, bamboo (4)" , "A stick to lean on" .)