Choice for each in U-boat? (6)
I believe the answer is:
superb
'choice' is the definition.
(I've seen this before)
'each in u-boat?' is the wordplay.
'each' becomes 'per' ('per' can mean for each).
'in' is an insertion indicator.
'u-boat?' becomes 'sub' (German submarine).
'per' going within 'sub' is 'SUPERB'.
'for' acts as a link.
(Other definitions for superb that I've seen before include "Dazzling" , "Highly impressive" , "Tiptop" , "'Excellent, splendid (6)'" , "Admirable" .)