African expedition is retreating, keeping at a distance (6)
I believe the answer is:
safari
'african expedition' is the definition.
(African hunting expedition)
'is retreating keeping at a distance' is the wordplay.
'retreating' shows that the letters should be reversed in order.
'keeping' means one lot of letters goes inside another.
'at a distance' becomes 'afar' (I've seen this before).
'is' backwards is 'si'.
'si' placed around 'afar' is 'SAFARI'.
(Other definitions for safari that I've seen before include "Wildlife-watching expedition" , "Overland journey to look for wild animals" , "As fair as an African expedition" , "Hunting journey" , "tropical trip" .)