Charity sporting official concealing untruth (6)
I believe the answer is:
relief
'charity' is the definition.
(thesaurus)
'sporting official concealing untruth' is the wordplay.
'sporting official' becomes 'ref' (short for referee).
'concealing' is an insertion indicator.
'untruth' becomes 'lie' (lie is a kind of untruth).
'ref' placed around 'lie' is 'RELIEF'.
(Other definitions for relief that I've seen before include "'Alleviation, easement (6)'" , "Break" , "Easement or assistance to people in need" , "Alleviation of anxiety" , "reserve" .)