Confusion over study about entrance to harbour (place a little way out to sea) (8)
I believe the answer is:
pierhead
'place a little way out to sea' is the definition.
'confusion over study about entrance to harbour' is the wordplay.
'confusion' becomes 'pie' (I've seen this in other clues).
'over study' becomes 'read' ('read' can be a synonym of 'study'. I am not sure about the 'over' bit.**).
'about' is an insertion indicator.
'entrance to' suggests taking the first letters.
The first letter of 'harbour' is 'h'.
'read' going around 'h' is 'rhead'.
'pie'+'rhead'='PIERHEAD'
(Other definitions for pierhead that I've seen before include "Seaward end of landing stage" , "One must walk on water to get there" .)