Hands down back of settee, a number of items not quite retrieved, unknown quantity (6)

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

[setteE] + a reversal (retrieved) of LIS[t] (number of items, not quite) + Y (unknown quantity) – read rather like a telegram, this paints a recognisable picture: we’ve all been there, I’m sure