Elevated exercise involving a Biblical character (4)
I believe the answer is:
esau
'biblical character' is the definition.
(I've seen this before)
'elevated exercise involving a' is the wordplay.
'elevated' is a reversal indicator (in a down clue, letters go up).
'exercise' becomes 'use' (synonyms).
'involving' means one lot of letters goes inside another.
'use' enclosing 'a' is 'uase'.
'uase' in reverse letter order is 'ESAU'.
(Other definitions for esau that I've seen before include "Hairy OT man" , "Biblical twin to Jacob" , "Old Testament twin" , "Cunning hunter" , "Isaac's hairy son" .)