Parliamentary constituency Swansea teacher captures (4)
I believe the answer is:
seat
'parliamentary constituency' is the definition.
(as in a seat in parliament)
'swansea teacher captures' is the wordplay.
'captures' indicates a hidden word (the answer is trapped within the clue).
'SEAT' is hidden within 'swansea teacher'.
(Other definitions for seat that I've seen before include "Box ---, position of advantage" , "Horizontal part of a chair" , "Chair, bench, or stool, say" , "See 10" , "Constituency; location" .)