Maiden king's taken in hand (5)
I believe the answer is:
first
'maiden' is the definition.
(synonyms)
'king's taken in hand' is the wordplay.
'king' becomes 'R' (abbreviation for rex, king in Latin).
'taken in' is an insertion indicator.
'hand' becomes 'fist' (hand curled into a fist).
'r' inserted within 'fist' is 'FIRST'.
(Other definitions for first that I've seen before include "Before all else" , "Rifts of supreme sort" , "Preceding all others" , "The one that precedes all others, in time say" , ""Eclipse _____ ..." .)