Shape emerges from half-hidden recess leading to confusion (9)
I believe the answer is:
rectangle
'shape' is the definition.
(rectangle is a kind of shape)
'half-hidden recess leading to confusion' is the wordplay.
'half-hidden' means to take half the letters.
'leading to' means one lot of letters go next to another (some letters go before or lead others).
'confusion' becomes 'tangle' (tangle is a kind of confusion**).
'recess' with half the letters taken is 'rec'.
'rec'+'tangle'='RECTANGLE'
'emerges from' is the link.
(Other definitions for rectangle that I've seen before include "Geometric figure with four right angles, not square" , "Oblong" , "box" , "regular sort of figure" , "Four-sided figure" .)