Saddle and take horse about midnight (5)
I believe the answer is:
ridge
'saddle' is the definition.
(I've seen this before)
'horse about midnight' is the wordplay.
'horse' becomes 'ride' ().
'about' is an insertion indicator.
'midnight' becomes 'g' (the middle letter in 'night').
'ride' enclosing 'g' is 'RIDGE'.
'and take' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for ridge that I've seen before include "Crest - reef" , "Peak" , "Narrow raised band on a surface" , "Top of a long narrow hill" , "drum" .)