Went by Underground the wrong way in the beginning (5)
I believe the answer is:
debut
'the beginning' is the definition.
(debut is a kind of beginning)
'went by underground the wrong way' is the wordplay.
'went by' becomes 'd' (I can't explain this - if you can you should believe this answer much more).
'underground' becomes 'tube' ('tube' can be a synonym of 'underground').
'the wrong way' shows that the letters should be reversed in order.
'tube' reversed gives 'ebut'.
'd'+'ebut'='DEBUT'
'in' is the link.
Can you help me to learn more?
(Other definitions for debut that I've seen before include "Introduction" , "Start -- launch" , "Initial appearance" , "Appear in public for the first time" , "First appearance in society" .)