"If I Only Had the Nerve” singer (8,4)
I believe the answer is:
cowardly lion
'if i only had the nerve singer' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for cowardly lion that I've seen before include "Would-be hero" , "[FRIEND OF DOROTHY] - with 21d" , "Cat going after bottle" .)