Top two maidens in action (6)
I believe the answer is:
summit
'top' is the definition.
(I know that top can be written as summit)
'two maidens in action' is the wordplay.
'two maidens' can mean two substitutions for 'maidens'.
'maidens' becomes 'm' (cricket abbreviation).
'maidens' becomes 'm' (cricket abbreviation).
'in' is an insertion indicator.
'action' becomes 'suit' (synonyms).
'm'+'m'='mm'
'mm' put within 'suit' is 'SUMMIT'.
(Other definitions for summit that I've seen before include "Highest point (of hill)" , "important meeting" , "Crown" , "Apex" , "The highest peak" .)