Dashed halfway back when dejected (3)
I believe the answer is:
sad
'dejected' is the definition.
(associated in meaning)
'dashed halfway back' is the wordplay.
'halfway' indicates taking half.
'back' shows that the letters should be reversed in order.
'dashed' with half the letters taken is 'das'.
'das' backwards is 'SAD'.
'when' acts as a link.
(Other definitions for sad that I've seen before include "Melancholy, triste" , "Melancholy, depressed" , "upset" , "Unhappy or melancholy" , "Mournful and depressed" .)