Physicist has May meeting with top man (7)
I believe the answer is:
hawking
'physicist' is the definition.
(I've seen this before)
'has may meeting with top man' is the wordplay.
'has may' becomes 'ha' (I can't explain this - if you can you should believe this answer much more).
'meeting' is a charade indicator (letters next to each other).
'with' becomes 'w' (abbreviation).
'top man' becomes 'king'.
'ha'+'w'+'king'='HAWKING'
(Other definitions for hawking that I've seen before include "Cosmologist attracted to 6 [BLACKHOLE] s" , "Physicist" , "clearing his throat noisily" , "Falconry - "Brief History" author" , "Peddling" .)