Very much losing my mind here. Any hints on the following clues would be much appreciated -
13a - CRAFT GENT GETTING 50% OFF
41a - PERHAPS SITTER STAYS FULFILLED
4D - TARGET BRIEFLY FAILED TO PASS CAMBRIDGE EXAM
44A has given me a hint at what the treatment is but I can't find a way to cram anything into 1D that'll fit and not make 13A nonsense. Samesies with 5A. Help please!!