The crossword solution for the term 'wizened up' is SERE, which stands for Survival, Evasion, Resistance, and Escape. This is a training program used by the United States military to prepare personnel for survival in hostile environments. It teaches them how to evade capture, resist interrogation, and escape from captivity. The phrase 'wizened up' implies that someone has become more knowledgeable and experienced in a particular area, which is what the SERE program does for its participants.