The goody-goody turned up before the train pulled out
I believe the answer is:
'the goody-goody' is the definition.
(thesaurus)
'turned up before the train pulled out' is the wordplay.
'turned up' says the letters should be written in reverse.
'before' becomes 'up' (I can't justify this - if you can you should believe this answer much more).
'pulled' is an anagram indicator (I've seen 'pulling' mean this).
'out' is an insertion indicator.
'up' written backwards gives 'pu'.
'train' is an anagram of 'ritan'.
'pu' going within 'ritan' is 'PURITAN'.
Can you help me to learn more?
(Other definitions for puritan that I've seen before include "Extreme moralist" , "Prude" , "Strictly moral person" , "One with very strict moral principles" , "One forgoing pleasure" .)