Fail to pick prize up — fifty in stock (4,1,5)
I believe the answer is:
draw a blank
'fail' is the definition.
(to draw a blank is to fail to think of something)
'pick prize up fifty in stock' is the wordplay.
I cannot really understand how this works, but
'fifty' could be 'l' (Roman numeral) and 'l' is present in the answer.
'stock' could be 'bank' (a large stock of something) and 'bank' is located in the remaining letters.
This may be the basis of the clue (or it may be nonsense).
'to' is the link.
(Other definitions for draw a blank that I've seen before include "In board game players like to" , "lucky in Russian roulette" , "Be unlucky in raffle" , "Get no result" , "Get no successful response" .)