Cricket sides in one period left with initially sore feet (7)
I believe the answer is:
dactyls
'feet' is the definition.
(dactyl is a kind of foot)
'cricket sides in one period left with initially sore' is the wordplay.
'sides' means to remove the middle letters (only the letters on the sides are used).
'in' indicates putting letters inside.
'one period' becomes 'day' (day is a kind of period).
'left with' becomes 'l' (common abbreviation. I am not sure about the 'with' bit.).
'initially' suggests taking the first letters.
'cricket' with its centre removed is 'ct'.
The first letter of 'sore' is 's'.
'ct' placed inside 'day' is 'dacty'.
'dacty'+'l'+'s'='DACTYLS'
Can you help me to learn more?