Colouring agent is something recalled in bamboo? (8)
I believe the answer is:
carotene
'colouring agent' is the definition.
(carotene is a pigment)
'something recalled in bamboo?' is the wordplay.
'something recalled' becomes 'rote' (as in learning by rote).
'in' is an insertion indicator.
'bamboo?' becomes 'cane' (cane-producing plant).
'rote' put inside 'cane' is 'CAROTENE'.
'is' is the link.
(Other definitions for carotene that I've seen before include "Reddish-yellow pigment" , "Orange plant pigment" , "Orange pigment converted to vitamin A in the liver" , "Colouring found in carrots" , "Orange stuff" .)