does it disapear when you press the clutch in?
if so it will be you thrust bearing in the gearbox, common fault and i would recommend getting it sorted asap, mine went after i left it for months, ended up getting towed home

lol
its a gearbox out job, so if your handy with the spanners, have a go. a bit fiddly but not to hard to do. get a haynes manual, takes you thro it step by step.
part is only a few quid from citroen.
or a good garage could do it for you.
hope that helps?
boz
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