African primate elevated Old Testament first (5)
I believe the answer is:
potto
'african primate' is the definition.
(type of primate found in Africa)
'elevated old testament first' is the wordplay.
'elevated' is a reversal indicator (in a down clue, letters go up).
'old testament' becomes 'ot'.
'first' becomes 'top' (top can mean the best or first).
'ot'+'top'='ottop'
'ottop' back-to-front is 'POTTO'.
(Other definitions for potto that I've seen before include "Nocturnal primate" , "Little creature" , "Kinkajou" , "Sort of 13 [LEMUR]" , "Slow-moving African" .)