Call for colonist seen in procession (7)
I believe the answer is:
pageant
'procession' is the definition.
(I've seen this before)
'call for colonist' is the wordplay.
'call for' becomes 'page' (to page is to call with a pager).
'colonist' becomes 'ant' (I've seen this before).
'page'+'ant'='PAGEANT'
'seen in' acts as a link.
(Other definitions for pageant that I've seen before include "Colourful procession" , "Make public spectacle" , "Parade with tableaux" , "Magnificent parade" , "Scene moving" .)