Fielder’s hand crossing rope initially by mistake (5,4)
I believe the answer is:
first slip
'mistake' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.
'fielder's hand crossing rope initially by' is the wordplay.
'fielder' becomes 'slip'.
'hand' becomes 'fist' (fist is a kind of hand).
'crossing' indicates putting letters inside.
'initially' says to take the initial letters.
'by' is a charade indicator (letters next to each other).
The initial letter of 'rope' is 'r'.
'fist' placed around 'r' is 'first'.
'slip' put after 'first' is 'FIRST SLIP'.
Can you help me to learn more?
(Another definition for first slip that I've seen is " could catch you out".)