Set alight during the Blitz (3)
I believe the answer is:
lit
'set alight' is the definition.
(I've seen this before)
'during the blitz' is the wordplay.
'during' indicates the answer is hidden within the clue.
'LIT' can be found hidden inside 'blitz'.
(Other definitions for lit that I've seen before include "Enlightened" , "fine writing in condensed form" , "books etc?" , "Illuminated" , "Settled" .)