The man with lots of money but not with the bosses (5)
I believe the answer is:
heads
'the bosses' is the definition.
'the man with lots of money but not with' is the wordplay.
'the man with' becomes 'he' (I can't justify this - if you can you should give a lot more credence to this answer).
'lots of money' becomes 'wads'.
'but not' indicates named letters should be taken away.
'with' becomes 'w' (abbreviation).
'wads' with 'w' taken out is 'ads'.
'he'+'ads'='HEADS'
(Other definitions for heads that I've seen before include "Noddles; nuts" , "Ship's latrine; addicts" , "Obverse of a coin" , "Obverse result of coin-tossing" , "School principals" .)