Movement to put first part of play on (6)
I believe the answer is:
action
'movement' is the definition.
(I've seen this in another clue)
'put first part of play on' is the wordplay.
'put' means one lot of letters goes inside another.
'first' becomes 'i' (Roman numeral for one or first).
'part of play' becomes 'act' (a play is made up of acts).
'act'+'on'='acton'
'i' put within 'acton' is 'ACTION'.
'to' acts as a link.
(Other definitions for action that I've seen before include "SECOND PART OF 15" , "Take proceedings" , "war?" , "Fighting - lawsuit" , "Lawsuit; something done" .)