Disparity (3)
'disparity' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for imbalance that I've seen before include "Unequal division" , "Disparity" , "disproportion" , "Lopsidedness" , "Asymmetry" .)
'disparity' is the definition.
(gap is a kind of disparity)
This is the entire clue.
(Other definitions for gap that I've seen before include "Space (maybe for a year?)" , "Narrow opening" , "Breach or lacuna" , "Fissure" , "A break or opening as in a hedge" .)