This is a reversal clue - look for indicators like 'back', 'returned', 'up' (in down clues), or 'west' (in across clues)
Reverse the letters of a word from the clue
Answer: OOHLALA | Definition: 'well!' | Wordplay: A charade of OOH, a reversal (‘arising’ in a down light) of HOO[k] (‘catchy phrase’) minus its last letter (‘short’); plus LA-LA (‘singing’), with perhaps a hint of an extended definition.