Boy briefly caught in hail overhead (5)
I believe the answer is:
above
'overhead' is the definition.
(I've seen this in another clue)
'boy briefly caught in hail' is the wordplay.
'briefly' means to remove the last letter.
'caught in' is an insertion indicator.
'hail' becomes 'ave' (greeting in Latin).
'boy' with its last letter removed is 'bo'.
'bo' put within 'ave' is 'ABOVE'.
(Other definitions for above that I've seen before include "Aloft" , "Position of the heavens!" , "In preference to" , "Superior to" , "At a higher level" .)