Flower: item for sale by our group (5)
I believe the answer is:
lotus
'flower' is the definition.
(I've seen this before)
'item for sale by our group' is the wordplay.
'item for sale' becomes 'lot' (I've seen this before).
'by' means one lot of letters go next to another.
'our group' becomes 'us'.
'lot'+'us'='LOTUS'
(Other definitions for lotus that I've seen before include "In myth, a plant whose fruit induced forgetfulness" , "Aquatic plant" , "A blooming" , "It helps with memory loss" , "Kind of water lily" .)