Horse and trap turning north: that's imminent (4)
I believe the answer is:
nigh
'imminent' is the definition.
(I've seen this in another clue)
'horse and trap turning' is the wordplay.
'horse' becomes 'H' (abbreviation as in horse power).
'and' means one lot of letters go next to another.
'trap' becomes 'gin' (gin trap is a kind of animal trap).
'turning' is a reversal indicator.
'gin' written backwards gives 'nig'.
'h' after 'nig' is 'NIGH'.
'north that's' 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 nigh that I've seen before include "'Almost, near (4)'" , "Near (old use)" , "Adjacent" , "Near (poetic)" , "in the vicinity?" .)