Try to bring in capsized buoy (7)
I believe the answer is:
hearten
'buoy' is the definition.
(I've seen this in another clue)
'try to bring in capsized' is the wordplay.
'try' becomes 'hear' (as in to try someone in court or hear their case).
'to bring in' becomes 'net' (I've seen this in another clue).
'capsized' shows that the letters should be reversed in order (in a down clue, the word turns upside down).
'net' reversed gives 'ten'.
'hear'+'ten'='HEARTEN'
(Other definitions for hearten that I've seen before include "Buoy" , "given cheer" , "Encourage in Teheran" , "Encourage or cheer in cardiac manner" , "Be encouraged" .)