Soldier at base tackling onset of shellshock gets to demobilise? (8)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

PARA (short for paratrooper = a soldier trained in parachuting) + LYE (a strongly alkaline substance = base, in chemical terminology), containing (tackling) the first letter (onset) of S [hellshock]. A question-mark for a loose definition: paralyse = stop someone or something from moving = the opposite of mobilise.