But you can get dirty as you do so (5)
I believe the answer is:
clean
'do so' is the definition.
'clean' can be an answer for 'do' (thesaurus). I am unsure of the 'so' bit.
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for clean that I've seen before include "Pure; well-defined" , "Remove dirt or stain" , "Honest" , "Unsoiled" , "Unspoiled" .)