Swelling troubling your eyelid, basically (4)
I believe the answer is:
stye
'swelling' is the definition.
(stye is a kind of swelling)
'troubling your eyelid basically' is the wordplay.
'troubling' becomes 'st' (I can't explain this - if you can you should give a lot more credence to this answer).
'basically' suggests taking the first letters (the first letter could be its root or base).
The first letters of 'your eyelid' is 'ye'.
'st'+'ye'='STYE'
Can you help me to learn more?
(Other definitions for stye that I've seen before include "Infected swelling of the eye" , "Red eye" , "swelling by organ" , "Tamworth residence" , "Eyelid affliction" .)