Even leading may be child's play (15)
I believe the answer is:
straightforward
'be child's play' is the definition.
(both can mean very easy)
'even leading' is the wordplay.
'even' becomes 'straight' ('straight' can be similar in meaning to 'even').
'leading' becomes 'forward'.
'straight'+'forward'='STRAIGHTFORWARD'
'may' is the link.
(Other definitions for straightforward that I've seen before include "Uncomplicated" , "Plain sailing" , "Right on!" , "That's simple" , "Honest, open" .)