Annoying person one's put in shade (8)
I believe the answer is:
nuisance
'annoying person' is the definition.
(I've seen this before)
'one's put in shade' is the wordplay.
'one's' becomes 'i's' (Roman numeral).
'put in' means one lot of letters goes inside another.
'shade' becomes 'nuance' (synonyms).
'is' put within 'nuance' is 'NUISANCE'.
(Other definitions for nuisance that I've seen before include "troublesome type" , "Bother" , "Irritant or botheration" , "Bothersome annoying person" , "Tiresome person or event" .)