Lily reveals a great deal to us (5)
I believe the answer is:
lotus
'lily' is the definition.
'a great deal to us' is the wordplay.
'a great deal' becomes 'lot' (both can mean a large amount).
'lot'+'us'='LOTUS'
'reveals' acts as a link.
(Other definitions for lotus that I've seen before include "Plant - yoga position" , "British sports and racing car manufacturer" , "Water-lily; yoga position" , "Type of water-lily" , "the indolent took for eating" .)