Fault-finding survey about old port (10)
I believe the answer is:
censorious
'fault-finding' is the definition.
(I've seen this before)
'survey about old port' is the wordplay.
'survey' becomes 'census' (I've seen this before).
'about' is an insertion indicator.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'port' becomes 'rio' (Rio de Janeiro is a port).
'o'+'rio'='orio'
'census' going around 'orio' is 'CENSORIOUS'.
(Other definitions for censorious that I've seen before include "Fault-finding" , "Severely critical" , "Blaming" , "making moral judgments?" .)