Artist bent over, inspired by unopened magic mushroom (6)
I believe the answer is:
agaric
'mushroom' is the definition.
(I've seen this before)
'artist bent over inspired by unopened magic' is the wordplay.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'bent over' says the letters should be written backwards.
'inspired by' indicates putting letters inside (some letters breathed in or 'inspired' by others).
'unopened' means to remove the first letter (without opening letter).
'ra' in reverse letter order is 'ar'.
'magic' with its initial letter removed is 'agic'.
'ar' inserted within 'agic' is 'AGARIC'.
(Other definitions for agaric that I've seen before include "Type of mushroom" , "fungal growth" , "Fungus of mushroom family" , "Fungus, eg, mushroom" .)