Unoccupied daughter replacing son in Skye, perhaps (4)
I believe the answer is:
idle
'unoccupied' is the definition.
(similar in meaning)
'daughter replacing son in skye perhaps' is the wordplay.
I cannot quite understand how this works, but
'daughter' could be 'd' (genealogical abbreviation) and 'd' is found in the answer.
The remaining letters 'ile' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
(Other definitions for idle that I've seen before include "Explosive stuff" , "Unoccupied (time); run (engine) slowly" , "Not busy" , "Do very little" , "Disliking work" .)