Pampered pet's first painting framed by good person (6)
I believe the answer is:
spoilt
'pampered' is the definition.
('spoilt' can be a synonym of 'pampered')
'pet's first painting framed by good person' is the wordplay.
'first' indicates taking the first letters.
'painting' becomes 'oil' (oil painting is a kind of painting).
'framed by' indicates putting letters inside.
'good person' becomes 'st' (saint).
The initial letter of 'pets' is 'p'.
'p'+'oil'='poil'
'poil' going within 'st' is 'SPOILT'.
(Other definitions for spoilt that I've seen before include "Went off" , "Overindulged" , "Ruined" , "messed up" , "Destroyed the value of" .)