Climbing plant concealing golden key (5)
I believe the answer is:
ivory
'key' is the definition.
(I've seen this before)
'climbing plant concealing golden' is the wordplay.
'climbing plant' becomes 'ivy' (ivy is a type of climbing plant).
'concealing' is an insertion indicator.
'golden' becomes 'or' ('or' is the name for gold in heraldry).
'ivy' placed around 'or' is 'IVORY'.
(Other definitions for ivory that I've seen before include "Creamy colour" , "Like the tower" , "Piano key" , "Key perhaps" , "Piano-key" .)