Bad ornamentation, having to decorate (5)
I believe the answer is:
adorn
'decorate' is the definition.
(synonyms)
'bad ornamentation having' is the wordplay.
'having' indicates the answer is hidden within the clue.
'ADORN' is hidden within 'bad ornamentation'.
'to' acts as a link.
(Other definitions for adorn that I've seen before include "Beautify - decorate - enhance" , "Embellish, decorate" , "dress" , "Make more attractive" , "get dressed!" .)