Bigwig hides underwear (surprise!) right in instrument (9)
I believe the answer is:
vibraharp
'instrument' is the definition.
(I know that vibraharp is a type of percussion instrument)
'bigwig hides underwear surprise right' is the wordplay.
'bigwig' becomes 'VIP' (I've seen this in another clue).
'hides' means one lot of letters goes inside another.
'underwear' becomes 'bra' (bra is a type of undergarment).
'surprise' becomes 'ha' (I've seen this in other clues).
'right' becomes 'r' (common abbreviation).
'bra'+'ha'+'r'='brahar'
'vip' enclosing 'brahar' is 'VIBRAHARP'.
'in' is the link.
(Other definitions for vibraharp that I've seen before include "music-maker" , "Music producer" .)