My start's somewhere down below
My middle's what sleep does bestow
My end's a value close enough
My whole's probably not that tough
What am I?
My start's somewhere down below
My middle's what sleep does bestow
My end's a value close enough
My whole's probably not that tough
What am I?
You are an:
UNDERESTIMATE
My start's somewhere down below
UNDER is a synonym for 'down below'.
My middle's what sleep does bestow
Sleep brings you REST.
My end's a value close enough
An ESTIMATE is an educated guess or an approximation ('close enough').
My whole's probably not that tough
An UNDERESTIMATE (i.e. something that has been underestimated) has been deemed 'probably not that tough' - but beware! Things aren't always what they seem, and may turn out tougher than you first think...
Post Script:
It seems from the title that the OP may have underestimated just how quickly this riddle would be solved!