Lily has filled bags with underwear, primarily (5)
I believe the answer is:
lotus
'lily' is the definition.
'filled bags with underwear primarily' is the wordplay.
'filled bags' becomes 'lots' (I can't explain this - if you can you should believe this answer much more).
'with' is an insertion indicator.
'primarily' indicates taking the first letters.
The initial letter of 'underwear' is 'u'.
'lots' placed around 'u' is 'LOTUS'.
'has' is the link.
Can you help me to learn more?
(Other definitions for lotus that I've seen before include "Kind of cross-legged position for meditation" , "TREE" , "Water lily - fruit inducing forgetfulness" , "----- Eaters, indolent hedonists" , "A blooming" .)