Man loves penguin (6)
I believe the answer is:
gentoo
'penguin' is the definition.
(I've seen this before)
'man loves' is the wordplay.
'man' becomes 'gent' (gent is a kind of man).
'loves' becomes 'oo' (two O's - 'love' means zero in tennis).
'gent'+'oo'='GENTOO'
(Other definitions for gentoo that I've seen before include "Breed of penguin" , "penguin on Goose Green!" , "bird from the Falklands" , "Variety of penguin" , "Two eggs sat upon by male" .)