Snack -- hopeless ultimately for giving to famous body-builder? (6)
I believe the answer is:
sarnie
'snack' is the definition.
(informal term for a sandwich)
'hopeless ultimately for giving to famous body-builder?' is the wordplay.
'ultimately' says to take the final letters.
'for giving to' is a charade indicator (letters next to each other).
'famous body-builder?' becomes 'Arnie' (nickname for Arnold Schwarzenegger).
The last letter of 'hopeless' is 's'.
's'+'arnie'='SARNIE'
(Other definitions for sarnie that I've seen before include "Familiar form of snack" , "Popular bread-based snack (colloq)" , "Sandwich (slang)" , "Two slices of bread with a filling" , "no classy fare" .)