Man Ray's art movement keeps Welshmen in check (7)
I believe the answer is:
dadaism
'welshmen in check' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'man ray's art movement' is the wordplay.
'man ray's art' becomes 'dada' (I've seen this in another clue).
'movement' becomes 'ism' (I've seen this in another clue).
'dada'+'ism'='DADAISM'
'keeps' acts as a link.
Can you help me to learn more?
(Other definitions for dadaism that I've seen before include "Anti-art movement" , "Absurd movement" , "artistic movement" , "Early twentieth century art movement" .)