The term 'ply' can refer to a variety of activities. To work is to engage in activity for the purpose of achieving a result, which can be done with four letters: 'work'. To PURSUE is to follow something with intent, which can be done with six letters: 'PURSUE'. To HANDLE is to take charge of or deal with something, which can also be done with six letters: 'HANDLE'. To BEND is to cause something to change its shape by applying pressure, which can be done with four letters: 'BEND'. To PRACTICE is to do something repeatedly in order to become proficient at it, which can be done with eight letters: 'PRACTICE'. To FOLD is to BEND something so that one part of it covers another, which can be done with four letters: 'FOLD'. To EXERCISE is to engage in physical activity in order to maintain fitness, which can be done with eight letters: 'EXERCISE'. To EMPLOY is to hire someone to do a job, which can be done with six letters: 'EMPLOY'. To LAYER is to arrange something in layers, which can be done with five letters: 'LAYER'. To WIELD is to have and USE power or influence, which can be done with five letters: 'WIELD'. Finally, to USE is to put something to a practical purpose, which can be done with three letters: 'USE'. To EXERT is to make an effort to do something, which can be done with five letters: 'EXERT'.