VIP with at least one major overhead (6)
I believe the answer is:
bigwig
'vip' is the definition.
(I've seen this in another clue)
'major overhead' is the wordplay.
'major' becomes 'big' (I've seen this in other clues).
'overhead' becomes 'wig' (I am not sure about this - if you are sure you should believe this answer much more).
'big'+'wig'='BIGWIG'
'with at least one' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for bigwig that I've seen before include "Somebody" , "'Chief, top banana (6)'" , "Mogul" , "Important person with large toupee" , "Important person (slang)" .)