Damned low returns in flashy jewellery (8)
I believe the answer is:
blooming
'damned' is the definition.
(thesaurus)
'low returns in flashy jewellery' is the wordplay.
'low' becomes 'moo' ('moo' can be a synonym of 'low').
'returns' says the letters should be written backwards.
'in' indicates putting letters inside.
'flashy jewellery' becomes 'bling' (I've seen this before).
'moo' backwards is 'oom'.
'oom' inserted within 'bling' is 'BLOOMING'.
(Other definitions for blooming that I've seen before include "Blossoming" , "Looking healthy" , "Healthy -- flowering" , "Euphemistic expletive - in flower" .)