LeClair began studying the instrument at age 11 and began her professional career at the age of 15 in a performance with the Philadelphia Orchestra playing the Mozart Sinfonia Concertante with colleagues from the Settlement Music School in Philadelphia, where she studied with Shirley Curtiss.

John Williams' bassoon concerto, The Five Sacred Trees, was written for LeClair and her "unparalleled artistry."

She premiered it in April 1995 as part of the New York Philharmonic's 150th anniversary festivities after having chosen him to receive the commission for the piece.

Her first teacher, a student, owned the bassoon; after he died in an accident at the age of 19, LeClair's parents bought the instrument from the boy's family.

In addition to her orchestral career, LeClair is also an active chamber musician and has taught numerous masterclasses.