Poland blocks cruises at sea displaying religious clothing (9)

'religious clothing' is the definition.
(surplices matches up with the definition religious clothing)

'poland blocks cruises at sea' is the wordplay.
'poland' becomes 'PL' (e.g. on number plates).
'blocks' indicates putting letters inside (upper walls off glass inside formal).
'at sea' indicates an anagram.
'cruises' anagrammed gives 'surices'.
'pl' going inside 'surices' is 'SURPLICES'.

'displaying' is the link.