Possible Clues:

• Enter surreptitiously, as an organization
• With revision, Fine Art & Lit gradually sink in
• Marching one abreast, crossing middle of hostile desert, enter secretly
• Slowly and secretly gain access to (an organisation)
• Gatecrash and fit in later, having mingled
• Sneak into modern army detachment, keeping floozie back
• Worm one's way into