Answer: splitter

AnswerCrossword Clue
SPLITTERAbe, the Rail-...
SPLITTERAbe at the rails
SPLITTERIt's in some pitchers' repertoires
splitterone that splits (to separate lengthwise)
splitterA person or thing occupied in or designed for splitting something
splitterA person, esp. a taxonomist, who attaches more importance to differences than to similarities in classification