This one can mount obstacles and will demonstrate warm clothing (10)
I believe the answer is:
showjumper
'this one can mount obstacles' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'will demonstrate warm clothing' is the wordplay.
'will' says to put letters next to each other (I've seen this in other clues).
'demonstrate' becomes 'show' (synonyms).
'warm clothing' becomes 'jumper'.
'show'+'jumper' is 'SHOWJUMPER'.
'and' is the link.
Can you help me to learn more?
(Other definitions for showjumper that I've seen before include "horse" , "one tackling obstacles in due course" , "performer in event" , "Sportsman" , "equestrian" .)