Wretch thus adopting tot (5)
I believe the answer is:
saddo
'wretch' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'thus adopting tot' is the wordplay.
'thus' becomes 'so' (synonyms).
'adopting' means one lot of letters goes inside another.
'tot' becomes 'add' (synonyms).
'so' going around 'add' is 'SADDO'.
Can you help me to learn more?
(Other definitions for saddo that I've seen before include "nerdy type" , "pathetic person" , "lonely person" , "Boring loner" , "loser" .)