Regularly seize catches soldier dropped when returning throw (6)

'regularly seize catches' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'soldier dropped when returning throw' is the wordplay.
I cannot really see how this works, but
'soldier' could be 'ra' (member of the Royal Artillery) and 'ra' is located in the answer.
'when' could be 'e' (I've seen this in other clues) and 'e' is located in the answer.
The remaining letters 'zap' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

Can you help me to learn more?