Solvent officer originally occupying an apartment (6)
I believe the answer is:
afloat
'solvent' is the definition.
(I've seen this before)
'officer originally occupying an apartment' is the wordplay.
'originally' indicates taking the first letters.
'occupying' is an insertion indicator.
'an' becomes 'a'.
'apartment' becomes 'flat' ('flat' can be a synonym of 'apartment').
The first letter of 'officer' is 'o'.
'a'+'flat'='aflat'
'o' going into 'aflat' is 'AFLOAT'.
(Other definitions for afloat that I've seen before include "Out of debt; at sea" , "On board at sea, on ship" , "get out of debt" , "At sea - in circulation" , "Buoyant: solvent" .)