Outputting the results of two select queries on to a single table in Oracle SQL
Look into GROUP BY queries.

SELECT gender, sum(PRICE) / count(*)
FROM ITEM, ITEM_CLOTHING 
WHERE ITEM.ITEM_ID = ITEM_CLOTHING.ITEM_ID
GROUP BY gender;


Or to refactor further:

SELECT gender, AVG(Price) AveragePrice
FROM ITEM
JOIN ITEM_CLOTHING ON ITEM.ITEM_ID = ITEM_CLOTHING.ITEM_ID
GROUP BY gender;