Petite iron designed for one with a suit (10)
I believe the answer is:
petitioner
'one with a suit' is the definition.
(I've seen this before)
'petite iron designed' is the wordplay.
'designed' is an anagram indicator (designed with the letters).
'petite'+'iron'='petiteiron'
'petiteiron' with letters rearranged gives 'PETITIONER'.
'for' acts as a link.
(Other definitions for petitioner that I've seen before include "One with a suit" , "One making appeal to authority" .)