Allowing girl showy jewellery (8)
I believe the answer is:
enabling
'allowing' is the definition.
'girl showy jewellery' is the wordplay.
'girl' becomes 'ena' (I've seen this in other clues).
'showy jewellery' becomes 'bling' (I've seen this before).
'ena'+'bling'='ENABLING'
(Other definitions for enabling that I've seen before include "Giving power to make possible" , "Giving authority or means to do something" , "Being permissive" , "Authorising" , "Empowering" .)