Go into parts designed for leading character (11)
I believe the answer is:
protagonist
'leading character' is the definition.
(I've seen this before)
'go into parts designed' is the wordplay.
'designed' is an anagram indicator (designed with the letters).
'go'+'into'+'parts'='gointoparts'
'gointoparts' anagrammed gives 'PROTAGONIST'.
'for' acts as a link.
(Other definitions for protagonist that I've seen before include "Leading character in a play, novel, etc" , "Lead character" , "Hero" , "Chief character in a story" , "Leading player" .)