Want to return home, having the key to get in (4)
I believe the answer is:
need
'want' is the definition.
(synonyms)
'key to get in' is the wordplay.
'key' becomes 'd' (I've seen this in other clues).
'to' means one lot of letters go next to another (I've seen this in other clues).
'get in' becomes 'nee' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'd' put after 'nee' is 'NEED'.
'to return home having the' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for need that I've seen before include "privation" , "Distressful situation" , "must have results!" , "state requiring relief" , "Necessity" .)