Start to play a part with Evita cast (8)
I believe the answer is:
activate
'start' is the definition.
(I've seen this before)
'play a part with evita cast' is the wordplay.
'play a part' becomes 'act' (I've seen this before).
'with' means one lot of letters go next to another.
'cast' is an anagram indicator (letters are dispersed or cast around).
'evita' with letters rearranged gives 'ivate'.
'act'+'ivate'='ACTIVATE'
'to' is the link.
(Other definitions for activate that I've seen before include "Stimulate to action" , "Switch on" , "Put in motion" , "Put into operation" , "Start, mobilise" .)