Notice colonist eating bun that's rich (8)
I believe the answer is:
abundant
'rich' is the definition.
(associated in meaning)
'notice colonist eating bun' is the wordplay.
'notice' becomes 'ad' (short for advert).
'colonist' becomes 'ant' (I've seen this in another clue).
'eating' means one lot of letters goes inside another.
'ad'+'ant'='adant'
'adant' enclosing 'bun' is 'ABUNDANT'.
'that's' acts as a link.
(Other definitions for abundant that I've seen before include "full" , "In plentiful supply" , "Guardian spirit" , "Luxuriant" , "'Copious, galore (8)'" .)