For each expert has it (3)
I believe the answer is:
per
'for each' is the definition.
('per' can mean for each)
'expert has it' is the wordplay.
'has it' indicates the answer is hidden within the clue.
'PER' is hidden within 'expert'.
(Other definitions for per that I've seen before include "Preposition meaning for each" , "Preposition indicating by means of" , "According to" , "For each or every" .)