Get back about allegation (7)
I believe the answer is:
reclaim
'get back' is the definition.
(I've seen this before)
'about allegation' is the wordplay.
'about' becomes 're' ('re' means regarding or about).
'allegation' becomes 'claim' (I've seen this in another clue).
're'+'claim'='RECLAIM'
(Other definitions for reclaim that I've seen before include "Miracle (anag)" , "Bring under cultivation" , "Recover (materials/land) for subsequent use" , "Win back" , "Convert" .)