Find out one's caught in port (8)
I believe the answer is:
discover
'find out' is the definition.
('discover' can be a synonym of 'find out')
'one's caught in port' is the wordplay.
'one's' becomes 'is' (Roman numeral).
'caught' becomes 'c' (cricket abbreviation).
'in' indicates putting letters inside.
'port' becomes 'dover' (I've seen this before).
'is'+'c'='isc'
'isc' put inside 'dover' is 'DISCOVER'.
(Other definitions for discover that I've seen before include "Find during a search" , "Find through searching" , "turn up" , "Detect, find" , "Come upon" .)