Droop, losing heart, or fall right down (4)
I believe the answer is:
drop
'fall right down' is the definition.
'drop' can be an answer for 'fall' (dropping is a kind of falling). I'm unsure of the 'right down' bit.
'droop losing heart' is the wordplay.
'losing heart' means to remove the middle letters.
'droop' with its centre taken out is 'DROP'.
'or' is the link.
Can you help me to learn more?
(Other definitions for drop that I've seen before include "Collapse, globule" , "Fail to hold" , "Fall; delivery" , "Fall down after prod" , "Shoot" .)