Stanhope changing to four-wheeled carriages (8)
I believe the answer is:
phaetons
'four-wheeled carriages' is the definition.
'phaetons' can be an answer for 'carriages' (I've seen this before). I'm not certain of the 'four-wheeled' bit.
'stanhope changing' is the wordplay.
'changing' indicates anagramming the letters.
'stanhope' anagrammed gives 'PHAETONS'.
'to' is the link.
Can you help me to learn more?
(Other definitions for phaetons that I've seen before include "So then Pa goes for large open cars with folding tops" , "Light horse-drawn carriages; six across(anag.)" .)