Of course I would need to be trained in it (6)
I believe the answer is:
indeed
'of course' is the definition.
(thesaurus)
'i would need to be trained in it' is the wordplay.
'i would' becomes 'id'.
'to be trained' indicates anagramming the letters (to train can mean to grow something into a shape).
'in it' is an insertion indicator.
'need' is an anagram of 'ndee'.
'id' enclosing 'ndee' is 'INDEED'.
(Other definitions for indeed that I've seen before include "Without question" , "still" , "Unquestionably" , "Really - truly" , "Yes, truthfully" .)