a treat

(do something) a treat

To do something very well, adeptly, or satisfactorily. Primarily heard in UK. After we oiled up the chain a bit, that old bike worked a treat. My daughter's singing went down a treat with the family members gathered at our house for Christmas. Wow, this suit fits a treat! It makes such a difference going to a tailor.
See also: treat
Farlex Dictionary of Idioms.

— a treat

used to indicate that someone or something does something specified very well or satisfactorily. British informal
1988 Ray Pickernell Yanto's Summer A flared cream pleated skirt that complemented those long perfect brown legs, and a powder blue tee shirt that matched her eyes a treat.
See also: treat
Farlex Partner Idioms Dictionary
See also:
  • (do something) a treat
  • treat
  • work a treat
  • get on (one's) bike
  • get on your bike
  • get off (one's) bike
  • get off your bike
  • chain (something) down
  • chain down
  • owe to