Cosmetic treatment - a lot of detail I allow having removed base (6)

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

Cosmetic treatment – a lot of detail, I allow, having removed base FAC <t> (=detail; “a lot of” means last letter only is dropped) + I AL <low> (“having removed base (=low, vile)” means letters “low” are dropped)