Frank, missing outsiders, dates person sitting exam? (9)
I believe the answer is:
candidate
'person sitting exam?' is the definition.
(candidate for a qualification)
'frank missing outsiders dates' is the wordplay.
'frank' becomes 'candid' (synonyms).
'missing outsiders' says to take the centre (letters on the outside are removed).
The centre of 'dates' is 'ate'.
'candid'+'ate'='CANDIDATE'
(Other definitions for candidate that I've seen before include "Detain cad seeking appointment" , "Competitor" , "who tries to get elected?" , "Campaigner" , "Applicant, nominee 99)" .)