Topless German soprano showing boobs (4)
I believe the answer is:
errs
'boobs' is the definition.
(I've seen this before)
'topless german soprano' is the wordplay.
'topless' means to remove the first letter.
'german' becomes 'herr'.
'soprano' becomes 's' (musical abbreviation).
'herr' with its initial letter taken off is 'err'.
'err'+'s'='ERRS'
'showing' is the link.
(Other definitions for errs that I've seen before include "Is mistaken" , "Sins" , "Goes astray" , "Makes mistakes" , "Slips up" .)