Small dose maybe overwhelming male player (5)
I believe the answer is:
'player' is the definition.
(I know that player can be written as thesp)
'small dose maybe overwhelming male' is the wordplay.
'small dose maybe' becomes 'tsp' (teaspoon).
'overwhelming' is an insertion indicator.
'male' becomes 'he' (he refers to a man).
'tsp' enclosing 'he' is 'THESP'.
(Another definition for thesp that I've seen is " ham".)