One is overwhelmed by ogre's howls (7)

'howls' is the definition.
(both can mean to cry or wail)

'one is overwhelmed by ogre's' is the wordplay.
'one' becomes 'i' (Roman numeral).
'is overwhelmed by' means one lot of letters goes inside another (inserted letters get absorbed or overwhelmed).
'ogre's' becomes 'Shrek's' (ogre in the film franchise).
'i' inserted inside 'shreks' is 'SHRIEKS'.