Whether you realise it or not, we look at a person’s clothes and make judgment calls based on them. For example, you would have a different impression of a stranger dressed in a suit than one in a football uniform.
When you’re writing, you build the character, so you need to reverse this process. Do you want your client to come across as a fussy musician? A scatterbrained teacher? A kindly grandparent? What sort of clothes would reflect this? What details could your detective pick up on that would help them to paint a picture of your client, without them saying a word?