Little old colonial outpost making mistake? (8)
I believe the answer is:
omission
'mistake?' is the definition.
(omission is a kind of mistake)
'little old colonial outpost' is the wordplay.
'little' says to take the initial letters.
'colonial outpost' becomes 'mission'.
The initial letter of 'old' is 'o'.
'o'+'mission'='OMISSION'
'making' acts as a link.
(Other definitions for omission that I've seen before include "Lack" , "Act of leaving out" , "Exclusion" , "Oversight, piece of work neglected" , "Deficiency" .)