Guy's partner, one meeting DiCaprio? The earth moved for him! (7)
I believe the answer is:
galileo
'earth moved for him' is the definition.
(Galileo said 'and yet it moves' about Earth)
'guy's partner one meeting dicaprio?' is the wordplay.
'guy's partner' becomes 'gal' (as in 'guys and gals').
'one' becomes 'i' (Roman numeral).
'meeting' means one lot of letters go next to another.
'dicaprio?' becomes 'leo' (Leonardo DiCaprio).
'gal'+'i'+'leo'='GALILEO'
'the' acts as a link.
(Other definitions for galileo that I've seen before include "He said Eppur si muove (But it does move)" , "US unmanned space-craft launched in 1989 to investigate Jupiter" , "Great Italian astronomer and physicist of 16th/17th century" , "Pioneer scientist" , "Great Italian astronomer and physicist of 17th century, suppressed by Church" .)