Allowed to go topless? Terrible! (5)
I believe the answer is:
awful
'terrible' is the definition.
(I know that terrible can be written as awful)
'allowed to go topless?' is the wordplay.
'allowed' becomes 'lawful' (I've seen this before).
'to go topless?' means to remove the first letter (I've seen 'going topless' mean this).
'lawful' with its initial letter taken off is 'AWFUL'.
(Other definitions for awful that I've seen before include "dire result" , "gruesome!" , "Fearsome" , "Dreadful, really bad" , "Atrocious, dire" .)