Severe punishment having caught one neglecting entomology for biology? (11)

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

LIFE S ent ENCE (severe punishment) excluding (neglecting) ENT [entomology]) and then containing (having) ( C [caught] + I [Roman numeral for one] ) in its place (for)  – giving CI replacing (for) ENT