Develop nothing after elevating half of nothing? (6)
I believe the answer is:
evolve
'develop' is the definition.
(I know that develop can be written as evolve)
'nothing after elevating half of nothing?' is the wordplay.
'nothing' becomes 'love' (love is zero in tennis).
'after elevating' says the letters should be written backwards (in a down clue, letters go up).
'half of' indicates taking half.
'nothing?' becomes 'love' (love is zero in tennis).
'love' reversed gives 'evol'.
'love' cut in half is 've'.
'evol'+'ve'='EVOLVE'
(Other definitions for evolve that I've seen before include "Cartoon sailor" , "Unravel" , "Unfold" , "Develop gradually over a long time" , "Develop by natural selection" .)