Swelling seen in chest yesterday (4)
I believe the answer is:
stye
'swelling' is the definition.
(I've seen this before)
'in chest yesterday' is the wordplay.
'in' indicates a hidden word.
'STYE' is hidden in the letters of 'chest yesterday'.
'seen' is the link.
(Other definitions for stye that I've seen before include "Viewer's complaint" , "Eye sore" , "Infection on the edge of the eye" , "Eye complaint" , "producing eyesore" .)