Participant not at first finding hen (5)
I believe the answer is:
'hen' is the definition.
(something which lays - eggs in this case)
'participant not at first' is the wordplay.
'participant' becomes 'player' (synonyms).
'not at first' means to remove the first letter.
'player' with its initial letter taken off is 'LAYER'.
'finding' is the link.
(Other definitions for layer that I've seen before include "(Separate) level" , "plate?" , "Single thickness and hen" , "Tier or thickness - or a hen?" , "Stratum or thickness" .)