One grand splashed out for something to make man a man? (8)
I believe the answer is:
androgen
'something to make man a man?' is the definition.
(male sex hormone)
'one grand splashed out' is the wordplay.
'splashed out' indicates anagramming the letters (letters splash or mix around).
'one'+'grand'='onegrand'
'onegrand' anagrammed gives 'ANDROGEN'.
'for' acts as a link.
(Other definitions for androgen that I've seen before include "Male hormone" , "Steroid" .)