Upright piano kept inside also got damaged (8)
I believe the answer is:
goalpost
'upright' is the definition.
(goalpost is a kind of upright)
'piano kept inside also got damaged' is the wordplay.
'piano' becomes 'p' (musical abbreviation).
'kept inside' is an insertion indicator.
'damaged' indicates an anagram.
'also'+'got'='alsogot'
'alsogot' with letters rearranged gives 'goalost'.
'p' going within 'goalost' is 'GOALPOST'.
(Other definitions for goalpost that I've seen before include "one unfairly moved" , "One propping up the bar" , "One of four supporters at ends of pitch" , "Upright with net attached" , "woodwork" .)