Surprising movement in platform in Embankment? (7)
I believe the answer is:
dadaism
'surprising movement' is the definition.
(unconventional 20th-century art movement)
'platform in embankment?' is the wordplay.
'platform' becomes 'dais' (dais is a kind of platform).
'in' indicates putting letters inside.
'embankment?' becomes 'dam' (I've seen this before).
'dais' inserted inside 'dam' is 'DADAISM'.
'in' acts as a link.
(Other definitions for dadaism that I've seen before include "artistic movement" , "Absurd movement" , "Early twentieth century art movement" , "Anti-art movement" .)