Already been discussed many times on here and answerbank.
Unless someone specifically reuests "hints only" I assume they are after the answer. If they don't get the answer on here they will be sure to get it elsewhere.
There are very few prize crosswords where the answers being given is actually frowned upon.(probably onlt the Listener on answerbank) It's a matter of preference. If you feel strongly then don't give answers.
It should be said that a lot of people who are "just starting out on cryptics" greatly value help on here particularly if an explanation of the parsing is given, so we should be encouraging them.
Whether the same people should be sending in their prize crosswords is a matter of conscience.