Meaning of “do sth up” - Learner’s Dictionary

do sth up

phrasal verb with do uk us /duː/ verb (past tense did, past participle done)
FASTEN mainly UK

to fasten something:

Do your coat up. It's cold outside.

B2 to repair or decorate a building so that it looks attractive

(Definition of “do sth up” from the Cambridge Learner’s Dictionary © Cambridge University Press)