One advantage of changing seats (5)
I believe the answer is:
asset
'one advantage' is the definition.
(I've seen this before)
'changing seats' is the wordplay.
'changing' is an anagram indicator.
'seats' with letters rearranged gives 'ASSET'.
'of' is the link.
(Other definitions for asset that I've seen before include "Useful or valuable quality or possession" , "Useful thing or person" , "Part of motor vehicle wheel" , "one liable to be stripped?" , "Something valuable to have" .)