Recasting Tosca during interval suited man's habit (9)
I believe the answer is:
waistcoat
'suited man's habit' is the definition.
(habit can mean clothing)
'recasting tosca during interval' is the wordplay.
'recasting' indicates an anagram.
'during' is an insertion indicator.
'interval' becomes 'wait' (wait is a kind of interval).
'tosca' is an anagram of 'stcoa'.
'stcoa' going into 'wait' is 'WAISTCOAT'.
(Other definitions for waistcoat that I've seen before include "American's vest" , "Sleeveless garment" , "Garment partly visible under a jacket" , "Clothing" , "Something worn" .)