Official SW trade changes (7)
I believe the answer is:
steward
'official' is the definition.
(I know that steward is a type of official)
'sw trade changes' is the wordplay.
'changes' indicates an anagram.
'sw'+'trade'='swtrade'
'swtrade' with letters rearranged gives 'STEWARD'.
(Other definitions for steward that I've seen before include "Airline cabin worker" , "Shipboard attendant" , "race course official" , "Sporting event supervisor" , "Ship/aircraft attendant" .)