Fifty in Panama fix position (9)
I believe the answer is:
placement
'position' is the definition.
(I know that position can be written as placement)
'fifty in panama fix' is the wordplay.
'fifty' becomes 'L' (Roman numeral).
'in' is an insertion indicator.
'panama' becomes 'pa'.
'fix' becomes 'cement' (cementing is a kind of fixing).
'l' inserted inside 'pa' is 'pla'.
'pla'+'cement'='PLACEMENT'
(Other definitions for placement that I've seen before include "period of work experience" , "Temporary posting" , "Temporary job for work experience" , "location" , "seating for dinner" .)