I'm professional with person 50% unsuitable (8)
I believe the answer is:
improper
'unsuitable' is the definition.
('improper' can be a synonym of 'unsuitable')
'i'm professional with person 50' is the wordplay.
'professional' becomes 'pro' ('pro' can be a synonym of 'professional').
'with' is a charade indicator (letters next to each other).
'50' suggests halving the letters.
'person' with half the letters taken is 'per'.
'im'+'pro'+'per'='IMPROPER'
(Other definitions for improper that I've seen before include "Indecent, unseemly" , "Unseemly, indelicate" , "Not conforming to norms of conduct, maybe indecent" , "Incorrect or wrong, say behaviour" , "Naughty" .)