Discover big game trip from a great distance (4)
I believe the answer is:
afar
'from a great distance' is the definition.
(I've seen this in another clue)
'discover big game trip' is the wordplay.
'discover' means to look at the middle letters (I've seen 'discovered' mean this (dis-covered - outer letters removed)).
'big game trip' becomes 'safari' (I've seen this before).
The centre of 'safari' is 'AFAR'.
(Other definitions for afar that I've seen before include "(From/at) a great distance" , "beyond the horizon" , "A long way away" , "quite some distance" , "Many miles away" .)