A Catholic on floating structure welcoming one from plane (8)
I believe the answer is:
aircraft
'plane' is the definition.
(I've seen this before)
'a catholic on floating structure welcoming one' is the wordplay.
'catholic' becomes 'RC' (abbreviation for Roman Catholic).
'on' is a charade indicator (letters next to each other).
'floating structure' becomes 'raft' (I've seen this before).
'welcoming' means one lot of letters goes inside another (in sense of 'inviting in').
'one' becomes 'i' (Roman numeral).
'a'+'rc'+'raft'='arcraft'
'arcraft' enclosing 'i' is 'AIRCRAFT'.
'from' is the link.
(Other definitions for aircraft that I've seen before include "Eg, seven four seven or Airbus" , "means of transport" , "Flying machines" , "Flying vehicle" , "Airbus A330 or A380, say" .)