Straightening leg Tin Man bust (9)
I believe the answer is:
alignment
'straightening' is the definition.
(I've seen this before)
'leg tin man bust' is the wordplay.
'bust' indicates an anagram.
'leg'+'tin'+'man'='legtinman'
'legtinman' anagrammed gives 'ALIGNMENT'.
(Other definitions for alignment that I've seen before include "Order" , "course" , "Act of straightening" , "Tin mangle (anag)" , "Arrangement in a straight line" .)