African resident agreed to be followed by a detective (5)
I believe the answer is:
okapi
'african resident' is the definition.
(animal native to Africa)
'agreed to be followed by a detective' is the wordplay.
'agreed' becomes 'ok' (e.g. when responding to offer).
'to be followed by' says to put letters next to each other.
'detective' becomes 'pi' (private eye).
'ok'+'a'+'pi'='OKAPI'
(Other definitions for okapi that I've seen before include "browser" , "Animal of central Africa" , "African relative of the giraffe" , "African leaves fancier" , "Ruminant related to the giraffe" .)