Fit in dock for computer (6)
I believe the answer is:
laptop
'for computer' is the definition.
(laptop is a kind of computer)
'fit in dock' is the wordplay.
'fit' becomes 'apt' (I've seen this in another clue).
'in' is an insertion indicator.
'dock' becomes 'lop' (both can mean to cut).
'apt' inserted within 'lop' is 'LAPTOP'.
(Other definitions for laptop that I've seen before include "Small computer" , "Aid for businessman" , "PC" , "Kind of computer" , "Some work on this" .)