Try, with courage running short (4)
I believe the answer is:
hear
'try' is the definition.
(as in to try someone in court or hear their case)
'courage running short' is the wordplay.
'courage' becomes 'heart' (heart is a kind of courage).
'running short' means to remove the last letter.
'heart' with its last letter taken away is 'HEAR'.
'with' acts as a link.
(Other definitions for hear that I've seen before include "Discover aurally" , "Listen to" , "Try (in court)" , "attend" , "Perceive with the ear" .)