Hide plain pants and fancy bloomers (9)
I believe the answer is:
delphinia
'fancy bloomers' is the definition.
(plural of delphinium, type of flowering plant)
'hide plain pants' is the wordplay.
'pants' indicates anagramming the letters (UK informal term for 'nonsense' or 'rubbish').
'hide'+'plain'='hideplain'
'hideplain' with letters rearranged gives 'DELPHINIA'.
'and' is the link.
(Other definitions for delphinia that I've seen before include "plants" , "Larkspurs" .)