title: Custom timestamp in emacs orgmode
body: <p>I'd like to insert a <strong>timestamp</strong> in a custom format in <strong>emacs orgmode</strong>. I want to insert just the current time (without date!) in this form: [HH:MM], by pressing <code>C-c -</code>. I am completely new to lisp and couldn't figure out how to do this.
  My starting point for my <code>~/.emacs</code>-file is like this:</p>
  
  <pre><code>(defun org-my-custom-timestamp ()
    (interactive)
    ( :SOME_CODE: )
  )
  
  
  (define-key global-map "\C-c-" 'org-my-custom-timestamp)
  </code></pre>
  
  <p>Now this is just the definition of my custom function called <code>org-my-custom-timestamp</code>, the "interactivation" and a Shortcut-assignment.
  However i have tried various things for <code>:SOME_CODE:</code> without any success.</p>
  
  <p>What can be fitted in the function to make it work in the described way?</p>
  
  <p>Does any experienced emacs-user even consider this way to tackle it practical or is there a smarter way to do it? Perhaps org-mode-internally?</p>