Papa is leader of men's movement (7)
I believe the answer is:
dadaism
'movement' is the definition.
(I know that dadaism is a type of art movement)
'papa is leader of men's' is the wordplay.
'papa' becomes 'dada' (synonyms).
'leader of' suggests taking the first letters.
The first letter of 'mens' is 'm'.
'dada'+'is'+'m'='DADAISM'
(Other definitions for dadaism that I've seen before include "artistic movement" , "Anti-art movement" , "Absurd movement" , "Early twentieth century art movement" .)