One inspired by celebrity’s instrument (5)
I believe the answer is:
sitar
'instrument' is the definition.
(sitar is a type of musical instrument)
'one inspired by celebrity's' is the wordplay.
'one' becomes 'i' (Roman numeral).
'inspired by' is an insertion indicator (some letters breathed in or 'inspired' by others).
'celebrity's' becomes 'star' (I've seen this before).
'i' inserted within 'star' is 'SITAR'.
(Other definitions for sitar that I've seen before include "instrument out east" , "Plucked instrument" , "Long-necked musical instrument of India" , "music producer" , "Long necked and often plucked" .)