You're lucky if he gives you a prize (5)
I believe the answer is:
ernie
'you're lucky if he gives you a prize' is the definition.
The definition suggests a singular noun which matches the answer.
This is all the clue.
Can you help me to learn more?
(Other definitions for ernie that I've seen before include "- - Bevin, 13 dn" , "- (the Fastest Milkman in the West) (Benny Hill)" , "Els, for example" , "Bondsman" , "Eric's other half" .)