Sentence:  His arm had been giving him some trouble and Rector was not enough of a medical expert to determine whether it had healed improperly or whether Hino was simply rebelling against the tedious work in the print shop , using the stiffness in his arm as an <WSD>excuse</WSD> . 
Meaning of the word marked with <WSD> tags:  a defense of some offensive behavior or some failure to keep a promise etc.