Genius is on test cricket ground (6,9)
I believe the answer is:
rocket scientist
'genius' is the definition.
(I've seen this in another clue)
'is on test cricket ground' is the wordplay.
'ground' is an anagram indicator ('grind' the letters into a new form).
'is'+'on'+'test'+'cricket'='isontestcricket'
'isontestcricket' with letters rearranged gives 'ROCKET SCIENTIST'.
(Other definitions for rocket scientist that I've seen before include "Clever chap" , "boffin" , "A high achiever" , "I launch farreaching studies" , "Mastermind" .)