
Zoe,
Sure there'll be better groomers than me along to give advice, but I would strongly suspect that clipping this area would make matters worse, not better .......
Having Collies, this area is a nightmare, best thing to do is just keep combing - and if you get a knot cut THROUGH it in the direction of hair growth (not across hairs to cut the whole knot off) - you should then find it will comb through fairly easily. Does that make sense?
M.