The initial idioms of the letter A

a chain is only as strong as its weakest link	risk of rain
a change in (one's) stripes	a change is as good as a rest
a change of heart	a change of pace
a change of tack	a charley horse
chatbot	a cheap shot
a chef d'oeuvre	cherry on top
a chicken and egg situation	a chicken in every pot
a chink in armour	a chinless wonder
a chip off the old block	a chip on (one's) shoulder
a chip on shoulder	a chunk of change
a civil question deserves a civil answer	a clarion call
a clean bill of health	a clean break
a clean sheet	a clean slate
a clean sweep	a clever clogs
a clever dick	a close call