In my case I needed to extend it like below

TASK_DEFINITION=$(aws ecs describe-task-definition --task-definition bespin | jq '.taskDefinition | del(.taskDefinitionArn) | del(.status) | del(.requiresAttributes) | del(.compatibilities) | del(.registeredAt) | del(.registeredBy) | del(.revision)')

echo $TASK_DEFINITION | jq '.containerDefinitions[0].image='\"${NEW_ECR_IMAGE}\"\ > task.json

aws ecs register-task-definition --family bespin --cli-input-json file://task.json