New Zealander Kelvin takes wicket in two (4)
I believe the answer is:
kiwi
'new zealander' is the definition.
(informal term for someone from New Zealand)
'kelvin takes wicket in two' is the wordplay.
'kelvin' becomes 'K' (abbreviation for the unit of temperature).
'takes' is a charade indicator (letters next to each other).
'wicket' becomes 'w'.
'in' is an insertion indicator.
'two' becomes 'II' (Roman numerals).
'w' placed into 'ii' is 'iwi'.
'k'+'iwi'='KIWI'
(Other definitions for kiwi that I've seen before include "Symbol of New Zealand" , "'Fruit, bird and NZ rugby player (4)'" , "apteryx" , "Fruit and flightless bird" , "Hairy fruit with green flesh" .)