Help please with parsing of three clues where I have answers but can't rationalise cryptic part of clues:
6D "Be constrained to make shame-faced attempt to succeed" (4-1-4). Must be "have a bash", but how does 'be constrained' and 'shame-faced' fit in?
16D "Forgiving one for tale-telling" (8). Must be "pardoner", but how does 'tale-telling' fit in?
26A "Chestnut that can come from the best or worst of commentators" (6). Must be "conker", but cannot rationalise any of clue except for 'chestnut'!!
Help appreciated